Document and Entity Information	12 Months Ended
Document and Entity Information	Dec. 31, 2018 shares
Document And Entity Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	JG
Entity Registrant Name	Aurora Mobile Ltd
Entity Central Index Key	0001737339
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Class A Common Shares
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	59,547,823
Class B Common Shares
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	17,000,189

CONSOLIDATED BALANCE SHEETS ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Current assets:
Cash and cash equivalents	¥ 576,562	$ 83,857	¥ 208,161
Restricted cash	115	17	115
Accounts receivable, net of allowances of RMB3,462 and RMB9,308 (US$1,354) as of December 31, 2017 and 2018, respectively	141,911	20,640	49,594
Prepayments and other current assets	80,578	11,719	34,228
Amounts due from related parties	4,564	664	1,260
Total current assets	803,730	116,897	293,358
Non-current assets:
Property and equipment, net	92,874	13,508	53,023
Intangible assets, net	1,531	223	283
Long-term investments	79,696	11,591	10,980
Other non-current assets	14,237	2,071	1,806
Total non-current assets	188,338	27,393	66,092
Total assets	992,068	144,290	359,450
Current liabilities:
Accounts payable (including accounts payable of the variable interest entity (“VIE”) without recourse to the Company of RMB8,340 and RMB18,683 (US$2,717) as of December 31, 2017 and 2018, respectively)	18,811	2,736	8,340
Deferred revenue and customer deposits (including deferred revenue and customer deposits of the VIE without recourse to the Company of RMB48,085 and RMB55,625 (US$8,091) as of December 31, 2017 and 2018, respectively)	59,483	8,651	49,557
Accrued liabilities and other current liabilities (including accrued liabilities and other current liabilities of the VIE without recourse to the Company of RMB31,631 and RMB59,556 (US$8,662) as of December 31, 2017 and 2018, respectively)	76,666	11,151	52,639
Amounts due to related parties (including amount due to related parties of the VIE without recourse to the Company of RMB459 and RMB8,864 (USD$1,289) as of December 31, 2017 and 2018, respectively)	8,864	1,289	6,110
Total current liabilities	163,824	23,827	116,646
Non-current liabilities:
Other non-current liabilities (including other non-current liabilities of the VIE without recourse to the Company of RMB216 and RMB140 (US$20) as of December 31, 2017 and 2018, respectively)	140	20	216
Deferred tax liabilities (including deferred tax liabilities of the VIE without recourse to the Company of RMB5 and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)			5
Deferred revenue (including deferred revenue of the VIE without recourse to the Company of RMB330 and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	10,265	1,493	330
Convertible notes (including deferred revenue of the VIE without recourse to the Company of RMB nil and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	216,179	31,442	0
Total non-current liabilities	226,584	32,955	551
Total liabilities	390,408	56,782	117,197
Commitments and contingencies
Mezzanine equity
Total mezzanine equity			466,637
Shareholders’ (deficit) equity
Common shares			26
Treasury shares (nil and 46,303 class A common shares as of December 31, 2017 and 2018, respectively)	(3,165)	(460)
Additional paid-in capital	944,500	137,372	13,689
Accumulated deficit	(348,123)	(50,632)	(234,810)
Accumulated other comprehensive loss	8,400	1,221	(3,289)
Total shareholders’ (deficit) equity	601,660	87,508	(224,384)
Total liabilities, mezzanine equity and shareholders’ deficit	992,068	144,290	359,450
Series A Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity			26,979
Series B Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity			52,723
Series C Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity			168,317
Series D Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity			¥ 218,618
Class A Common Shares
Shareholders’ (deficit) equity
Common shares	37	5
Class B Common Shares
Shareholders’ (deficit) equity
Common shares	¥ 11	$ 2

CONSOLIDATED BALANCE SHEETS (Parenthetical) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥) shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 CNY (¥) shares
Accounts receivable, net of allowances	¥ 9,308	$ 1,354	¥ 3,462
Accounts payable	18,811	2,736	8,340
Deferred revenue and customer deposits	33,067	4,809	28,921
Accrued liabilities and other current liabilities	76,666	11,151	52,639
Amount due to related parties	8,864	1,289	6,110
Other non-current liabilities	140	20	216
Deferred tax liabilities \| ¥			5
Deferred revenue	10,265	1,493	330
Convertible notes (including deferred revenue of the VIE without recourse to the Company of RMB nil and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	¥ 216,179	$ 31,442	¥ 0
Common shares, par value per share \| $ / shares		$ 0
Common shares, shares authorized	50,000,000	50,000,000	470,393,343
Common shares, shares issued	0	0	42,666,670
Common shares, shares outstanding	0	0	42,666,670
Series A Contingently Redeemable Convertible Preferred Shares
Contingently redeemable convertible preferred shares, par value per share \| $ / shares		$ 0
Contingently redeemable convertible preferred shares, shares authorized	0	0	11,111,120
Contingently redeemable convertible preferred shares, shares issued	0	0	11,111,120
Contingently redeemable convertible preferred shares, shares outstanding	0	0	11,111,120
Series B Contingently Redeemable Convertible Preferred Shares
Contingently redeemable convertible preferred shares, par value per share \| $ / shares		$ 0
Contingently redeemable convertible preferred shares, shares authorized	0	0	7,936,510
Contingently redeemable convertible preferred shares, shares issued	0	0	7,936,510
Contingently redeemable convertible preferred shares, shares outstanding	0	0	7,936,510
Series C Contingently Redeemable Convertible Preferred Shares
Contingently redeemable convertible preferred shares, par value per share \| $ / shares		$ 0
Contingently redeemable convertible preferred shares, shares authorized	0	0	4,999,540
Contingently redeemable convertible preferred shares, shares issued	0	0	4,999,540
Contingently redeemable convertible preferred shares, shares outstanding	0	0	4,999,540
Series D Contingently Redeemable Convertible Preferred Shares
Contingently redeemable convertible preferred shares, par value per share \| $ / shares		$ 0
Contingently redeemable convertible preferred shares, shares authorized	0	0	5,559,487
Contingently redeemable convertible preferred shares, shares issued	0	0	5,559,487
Contingently redeemable convertible preferred shares, shares outstanding	0	0	5,559,487
Class A Common Shares
Common shares, par value per share \| $ / shares		$ 0.0001
Common shares, shares authorized	4,920,000,000	4,920,000,000	0
Common shares, shares issued	59,547,823	59,547,823	0
Common shares, shares outstanding	59,547,823	59,547,823	0
Class B Common Shares
Common shares, par value per share \| $ / shares		$ 0.0001
Common shares, shares authorized	30,000,000	30,000,000	0
Common shares, shares issued	17,000,189	17,000,189	0
Common shares, shares outstanding	17,000,189	17,000,189	0
VIE
Accounts payable	¥ 18,683	$ 2,717	¥ 8,340
Deferred revenue and customer deposits	55,625	8,091	48,085
Accrued liabilities and other current liabilities	59,556	8,662	31,631
Amount due to related parties	8,864	1,289	459
Other non-current liabilities	140	20	216
Deferred tax liabilities	0	0	5
Deferred revenue	0	0	330
Convertible notes (including deferred revenue of the VIE without recourse to the Company of RMB nil and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	¥ 0	$ 0	¥ 0

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥) ¥ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 CNY (¥) ¥ / shares shares	Dec. 31, 2016 CNY (¥) ¥ / shares shares
Revenues (including related party amounts of RMB3,507 and RMB2,543 (US$370) for the years ended December 31, 2017 and 2018, respectively)	¥ 714,141	$ 103,868	¥ 284,709	¥ 70,322
Cost of revenues (including related party amounts of RMB788 and RMB19,763 (US$2,874) for the years ended December 31, 2017 and 2018, respectively)	(517,074)	(75,205)	(213,370)	(47,722)
Gross profit	197,067	28,663	71,339	22,600
Operating expenses
Research and development (including related party amounts of RMB762 and RMB200 (US$29) for the years ended December 31, 2017 and 2018, respectively)	(134,358)	(19,542)	(71,651)	(33,717)
Sales and marketing (including related party amounts of RMB541 and RMB178 (US$26) for the years ended December 31, 2017 and 2018, respectively)	(83,853)	(12,196)	(59,673)	(33,062)
General and administrative (including related party amounts of RMB138 and RMB59 (US$9) for the years ended December 31, 2017 and 2018, respectively)	(71,641)	(10,419)	(32,431)	(13,480)
Total operating expenses	(289,852)	(42,157)	(163,755)	(80,259)
Loss from operations	(92,785)	(13,494)	(92,416)	(57,659)
Foreign exchange (loss)/ gain, net	264	38	(2,724)	(328)
Interest income	3,657	532	314	283
Interest expense	(7,054)	(1,026)	(122)
Other income	8,449	1,229	677	232
Change in fair value of derivative liability	21,302	3,098
Loss before income taxes	(66,167)	(9,623)	(94,271)	(57,472)
Income tax (expense) benefit	(30)	(4)	3,980	(3,910)
Net loss	(66,197)	(9,627)	(90,291)	(61,382)
Net loss attributable to Aurora Mobile Limited’s shareholders	(66,197)	(9,627)	(90,291)	(61,382)
Accretion of contingently redeemable convertible preferred shares	(24,094)	(3,504)	(26,391)	(12,427)
Net loss attributable to common shareholders	(90,291)	(13,131)	¥ (116,682)	¥ (73,809)
Net loss per share for class A and class B common shares:
Common shares - basic and diluted \| ¥ / shares			¥ (2.73)	¥ (1.73)
Shares used in net loss per share computation:
Common shares - basic and diluted			42,666,670	42,666,670
Other comprehensive income (loss)
Foreign currency translation adjustments	11,688	1,700	¥ (7,563)	¥ 1,896
Total other comprehensive income (loss), net of tax	11,688	1,700	(7,563)	1,896
Total comprehensive loss	(54,509)	(7,927)	(97,854)	(59,486)
Comprehensive loss attributable to Aurora Mobile Limited	(54,509)	(7,927)	¥ (97,854)	¥ (59,486)
Class A Common Shares
Operating expenses
Net loss attributable to Aurora Mobile Limited’s shareholders	(46,606)	(6,779)
Accretion of contingently redeemable convertible preferred shares	(16,963)	(2,467)
Net loss attributable to common shareholders	¥ (63,569)	$ (9,246)
Net loss per share for class A and class B common shares:
Common shares - basic and diluted \| (per share)	¥ (1.57)	$ (0.23)
Shares used in net loss per share computation:
Common shares - basic and diluted	40,441,999	40,441,999
Class B Common Shares
Operating expenses
Net loss attributable to Aurora Mobile Limited’s shareholders	¥ (19,591)	$ (2,848)
Accretion of contingently redeemable convertible preferred shares	(7,131)	(1,037)
Net loss attributable to common shareholders	¥ (26,722)	$ (3,885)
Net loss per share for class A and class B common shares:
Common shares - basic and diluted \| (per share)	¥ (1.57)	$ (0.23)
Shares used in net loss per share computation:
Common shares - basic and diluted	17,000,189	17,000,189

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Parenthetical) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Statement Of Income And Comprehensive Income [Abstract]
Revenues - related parties	¥ 2,543	$ 370	¥ 3,507
Cost of revenues - related party	19,763	2,874	788
Research and development - related party	200	29	762
Sales and Marketing - related party	178	26	541
General and administrative - related party	¥ 59	$ 9	¥ 138

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT ¥ in Thousands, $ in Thousands	CNY (¥)	USD ($)	Common Stock CNY (¥) shares	Common Stock USD ($) shares	Treasury Stock CNY (¥)	Treasury Stock USD ($)	Additional Paid-in Capital CNY (¥)	Additional Paid-in Capital USD ($)	Accumulated Other Comprehensive Income CNY (¥)	Accumulated Other Comprehensive Income USD ($)	Accumulated Deficit CNY (¥)	Accumulated Deficit USD ($)
Balance at Dec. 31, 2015	¥ (40,204)		¥ 26				¥ 1,711		¥ 2,378		¥ (44,319)
Balance, Shares at Dec. 31, 2015 \| shares			42,666,670	42,666,670
Net loss attributable to Aurora Mobile Limited’s shareholders	(61,382)										(61,382)
Other comprehensive loss	1,896								1,896
Contribution from shareholder	1,000						1,000
Accretion of contingently redeemable convertible preferred shares	(12,427)										(12,427)
Share-based compensation	2,703						2,703
Balance at Dec. 31, 2016	(108,414)		¥ 26				5,414		4,274		(118,128)
Balance, Shares at Dec. 31, 2016 \| shares			42,666,670	42,666,670
Net loss attributable to Aurora Mobile Limited’s shareholders	(90,291)										(90,291)
Other comprehensive loss	(7,563)								(7,563)
Accretion of contingently redeemable convertible preferred shares	(26,391)										(26,391)
Share-based compensation	8,275						8,275
Balance at Dec. 31, 2017	(224,384)		¥ 26				13,689		(3,289)		(234,810)
Balance, Shares at Dec. 31, 2017 \| shares			42,666,670	42,666,670
Net loss attributable to Aurora Mobile Limited’s shareholders	(66,197)	$ (9,627)									(66,197)
Other comprehensive loss	11,689								11,689
Issuance of Class A common shares in connection with initial public offering	464,380		¥ 4				464,376
Issuance of Class A common shares in connection with initial public offering, Shares \| shares			6,059,708	6,059,708
Conversion of all outstanding contingently redeemable convertible preferred shares to Class A common shares	401,691		¥ 18				357,222				44,451
Conversion of all outstanding contingently redeemable convertible preferred shares to Class A common shares, Shares \| shares			27,867,937	27,867,937
Redemption of contingently redeemable convertible preferred shares	(6,915)										(6,915)
Accretion of contingently redeemable convertible preferred shares							84,652				(84,652)
Repurchased shares	(3,165)				¥ (3,165)
Repurchased shares, Shares \| shares			(46,303)	(46,303)
Share-based compensation	24,561						24,561
Balance at Dec. 31, 2018	¥ 601,660	$ 87,508	¥ 48	$ 7	¥ (3,165)	$ (460)	¥ 944,500	$ 137,372	¥ 8,400	$ 1,222	¥ (348,123)	$ (50,632)
Balance, Shares at Dec. 31, 2018 \| shares			76,548,012	76,548,012

CONSOLIDATED STATEMENTS OF CASH FLOWS ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Cash flows from operating activities:
Net loss	¥ (66,197)	$ (9,627)	¥ (90,291)	¥ (61,382)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	18,084	2,630	8,805	3,433
Amortization of intangible assets	307	45	35	0
Unrealized exchange (gain) loss	11,689	1,700	339	(369)
Allowance for doubtful accounts	5,846	850	2,427	1,049
Deferred tax expense (benefit)	(5)	(1)	(3,980)	3,910
Share-based compensation	24,561	3,572	8,275	2,703
Changes in operating assets and liabilities,
Accounts receivable	(98,163)	(14,278)	(48,266)	(5,870)
Prepayments and other current assets	(46,350)	(6,741)	(21,558)	(11,233)
Amounts due from related parties	(3,303)	(480)	(1,169)	(65)
Other non-current assets	(1,431)	(208)	(492)
Accounts payable	10,471	1,523	13,015	822
Deferred revenue and customer deposits	19,861	2,889	31,144	11,018
Accrued liabilities and other current liabilities	24,027	3,495	26,503	14,469
Amounts due to related parties	2,754	401	(243)	676
Change in deferred tax liabilities	(5)	(1)
Other non-current liabilities	(76)	(11)	(76)	(1,313)
Net cash used in operating activities	(97,925)	(14,241)	(75,532)	(42,152)
Cash flows from investing activities:
Purchase of time deposits				(10,000)
Proceeds from maturity of time deposits			10,053
Increase in long-term prepayment	(11,000)	(1,600)
Purchase of long-term investment	(68,716)	(9,994)	(10,000)	(1,041)
Purchase of property and equipment	(57,934)	(8,426)	(28,378)	(18,887)
Purchase of intangible assets	(1,556)	(226)	(319)
Net cash used in investing activities	(139,206)	(20,246)	(28,644)	(29,928)
Cash flows from financing activities:
Proceeds from issuance of contingently redeemable convertible preferred shares, net of issuance cost	216,179	31,442	217,446	134,348
Proceeds from initial public offering, net of issuance cost	464,380	67,541
Redemption of contingently redeemable convertible preferred shares	(62,510)	(9,092)
Repurchase of ordinary shares	(3,165)	(460)
Contribution from shareholder				1,000
Net cash provided by financing activities	614,884	89,431	217,446	135,348
Effect of exchange rate on cash and cash equivalents and restricted cash	(9,352)	(1,362)	(8,282)	2,450
Net increase in cash and cash equivalents and restricted cash	368,401	53,582	104,988	65,718
Cash, cash equivalents and restricted cash at the beginning of year	208,276	30,292	103,288	37,570
Cash and cash equivalents at the beginning of the year	208,161	30,276	103,168	37,570
Restricted cash at the beginning of the year	115	17	120
Cash, cash equivalents and restricted cash at the end of year	576,677	83,874	208,276	103,288
Cash and cash equivalents at the end of the year	576,562	83,857	208,161	103,168
Restricted cash at the end of the year	115	17	115	¥ 120
Supplemental disclosures of cash flow information:
Interest expense paid			122
Purchase of property and equipment included in accrued liabilities and other current liabilities	¥ 104	$ 15	¥ 9,731

Organization and Principal Activities

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Principal Activities

1	Organization and principal activities

Aurora Mobile Limited (the “Company” and where appropriate, the term “Company” also refers to its subsidiaries and variable interest entity) is a limited company incorporated in the Cayman Islands under the laws of the Cayman Islands on April 9, 2014. The Company, through its subsidiaries and variable interest entity (“VIE”), are principally engaged in providing data solutions which include targeted marketing, industry insights, financial risk management and location-based intelligence services in the People’s Republic of China (the “PRC”).

As PRC laws and regulations prohibit and restrict foreign ownership of internet value-added businesses, the Company operates its business, primarily through the VIE. The Company, through JPush Information Consulting (Shenzhen) Co., Ltd. (“Shenzhen JPush” or “WFOE”) entered into powers of attorney and an exclusive option agreement with the nominee shareholders of the VIE, that gave WFOE the power to direct the activities that most significantly affect the economic performance of the VIE and to acquire the equity interests in the VIE when permitted by the PRC laws, respectively. In addition, pursuant to the supplementary agreements signed in March, 2018, the rights under the aforementioned power of attorney and the exclusive call option agreements were assigned to the board of directors of the Company (the “Board”) or any officer authorized by the Board, which entitled the Company to receive economic benefits from the VIE that potentially could be significant to the VIE.

Despite the lack of technical majority ownership, the Company has effective control of the VIE through a series of VIE agreements and a parent-subsidiary relationship exists between the Company and the VIE. Through the VIE agreements and the supplementary agreements, the shareholders of the VIE effectively assigned all of their voting rights underlying their equity in the VIE to the Company. In addition, through the exclusive business operation agreement, the Company, through its WFOE in the PRC, have the right to receive economic benefits from the VIE that potentially could be significant to the VIE. Lastly, through the financial support agreement and the shareholder voting proxy agreement, the Company has the obligation to absorb losses of the VIE that could potentially be significant to the VIE. Therefore, the Company is considered the primary beneficiary of the VIE and consolidates the VIE as required by SEC Regulation S-X Rule 3A-02 and Accounting Standards Codification (“ASC”) 810.

The following is a summary of the VIE agreements:

Exclusive Option Agreements

Pursuant to the exclusive option agreements entered into between VIE’s nominee shareholders and the WFOE, the nominee shareholders irrevocably granted the WFOE an option to request the nominee shareholders to transfer or sell any part or all of its equity interests in the VIE, or any or all of the assets of the VIE, to the WFOE, or their designees. The purchase price of the equity interests in the VIE is equal to the minimum price required by PRC law. Without the WFOE’s prior written consent, the VIE and its nominee shareholders cannot amend its articles of association, increase or decrease the registered capital, sell or otherwise dispose of its assets or beneficial interest, create or allow any encumbrance on its assets or other beneficial interests and provide any loans or guarantees. The nominee shareholders cannot request any dividends or other form of assets. If dividends or other form of assets were distributed, the nominee shareholders are required to transfer all received distribution to the WFOE or their designees. These agreements are not terminated until all of the equity interest of the VIE is transferred to the WFOE or the person(s) designated by the WFOE. None of the nominee shareholders have the right to terminate or revoke the agreements under any circumstance unless otherwise regulated by law.

Equity Interest Pledge Agreements

Pursuant to the equity interest pledge agreements, each nominee shareholder of the VIE has pledged all of their respective equity interests in the VIE to WFOE as continuing first priority security interest to guarantee the performance of their and the VIE’s obligations under the powers of attorney agreement, the exclusive option agreement and the exclusive business cooperation agreement. WFOE is entitled to all dividends during the effective period of the share pledge except as it agrees otherwise in writing. If VIE or any of the nominee shareholder breaches its contractual obligations, WFOE will be entitled to certain rights regarding the pledged equity interests, including receiving proceeds from the auction or sale of all or part of the pledged equity interests of VIE in accordance with PRC law. None of the nominee shareholders shall, without the prior written consent of WFOE, assign or transfer to any third party, distribute dividends and create or cause any security interest and any liability in whatsoever form to be created on, all or any part of the equity interests it holds in the VIE. This agreement is not terminated until all of the technical support and consulting and service fees have been fully paid under the exclusive business cooperation agreement and all of VIE’s obligations have been terminated under the other controlling agreements. On December 16, 2014, the Company registered the equity pledge with the relevant office of the administration for industry and commerce in accordance with the PRC Property Rights Law.

1	Organization and principal activities (continued)

Exclusive Business Cooperation Agreement

Pursuant to the exclusive business cooperation agreement entered into by WFOE and VIE, WFOE provides exclusive technical support and consulting services in return for an annual service fee based on a certain percentage of the VIE’s audited total operating income, which is adjustable at the sole discretion of WFOE. Without WFOE’s consent, the VIE cannot procure services from any third party or enter into similar service arrangements with any other third party, except for those from WFOE. In addition, the profitable consolidated VIE has granted WFOE an exclusive right to purchase any or all of the business or assets of each of the profitable consolidated VIE at the lowest price permitted under PRC law. This agreement is irrevocable or can only be unilaterally revoked/amended by WFOE.

Powers of Attorney

Pursuant to the powers of attorney signed between VIE’s nominee shareholders and WFOE, each nominee shareholder irrevocably appointed WFOE as its attorney-in-fact to exercise on each shareholder’s behalf any and all rights that each shareholder has in respect of its equity interest in VIE (including but not limited to executing the exclusive right to purchase agreements, the voting rights and the right to appoint directors and executive officers of VIE). This agreement is effective and irrevocable as long as the nominee shareholder remains a shareholder of VIE.

In March 2018, the following supplementary agreements were entered into:

Financial Support Agreement

Pursuant to the financial support undertaking letter dated March 28, 2018, the Company is obligated to provide unlimited financial support to the VIE, to the extent permissible under the applicable PRC laws and regulations. The Company will not request repayment of the loans or borrowings if the VIE or its shareholders do not have sufficient funds or are unable to repay.

Shareholder Voting Proxy Agreement

The Nominee Shareholders also re-signed the powers of attorney agreement whereby they granted an irrevocable proxy of the voting rights underlying their respective equity interests in VIE from the WFOE to the Company, which includes, but are not limited to, all the shareholders’ rights and voting rights empowered to the Nominee Shareholders by the company law and the Company’s Article of Association.

Accordingly, as a result of the power to direct the activities of the VIE pursuant to the powers of attorney agreement and the obligation to absorb the expected losses of VIE through the unlimited financial support, the WFOE ceased to be the primary beneficiary and the Company became the primary beneficiary of the VIE on March 28, 2018.

In the opinion of the Company’s legal counsel, (i) the ownership structure of the PRC subsidiary and the VIE are in compliance with the existing PRC laws and regulations; (ii) each of the VIE agreements is valid, binding and enforceable in accordance with its terms and applicable PRC laws or regulations and will not violate applicable PRC laws or regulations in effect; and (iii) are valid in accordance with the articles of association of the Company.

However, uncertainties in the PRC legal system could cause the Company’s current ownership structure to be found in violation of existing and/or future PRC laws or regulations and could limit the Company’s ability to enforce its rights under these contractual arrangements. Furthermore, the nominee shareholders of the VIE may have interests that are different than those of the Company, which could potentially increase the risk that they would seek to act contrary to the terms of the contractual agreements with the VIE.

In addition, if the current structure or any of the contractual arrangements is found to be in violation of any existing or future PRC laws or regulations, the Company could be subject to penalties, which could include, but not be limited to, revocation of business and operating licenses, discontinuing or restricting business operations, restricting the Company’s right to collect revenues, temporary or permanent blocking of the Company’s internet platforms, restructuring of the Company’s operations, imposition of additional conditions or requirements with which the Company may not be able to comply, or other regulatory or enforcement actions against the Company that could be harmful to its business. The imposition of any of these or other penalties could have a material adverse effect on the Company’s ability to conduct its business.

1	Organization and principal activities (continued)

The following table set forth the assets and liabilities of the VIE included in the Company’s consolidated balance sheets:

	As of December 31,
	2017		2018
	RMB		RMB		US$
ASSETS:
Current assets:
Cash and cash equivalents		49,853		31,763		4,620
Restricted cash		115		115		17
Accounts receivable		49,561		141,705		20,609
Prepayments and other current assets		29,637		64,532		9,386
Amounts due from the Company and its subsidiaries		3,806		3,965		577
Amounts due from related parities		1,186		2,848		414
Total current assets		134,158		244,928		35,623
Non-current assets:
Long-term investments		10,000		71,512		10,401
Other receivables-non current		1,354		2,529		368
Property and equipment, net		24,258		46,271		6,730
Intangible assets, net		283		1,406		204
Long-term prepayment		—		11,000		1,600
Total non-current assets		35,895		132,718		19,303
Total assets		170,053		377,646		54,926
LIABILITIES:
Current liabilities:
Accounts payable		8,340		18,683		2,717
Deferred revenue and customer deposits		48,085		55,625		8,091
Accrued liabilities and other current liabilities		31,631		59,556		8,662
Amounts due to the Company and its subsidiaries		39,861		15,534		2,259
Amounts due to related parties		459		8,864		1,289
Total current liabilities		128,376		158,262		23,018
Non-current liabilities:
Amounts due to the Company and its subsidiaries		60,000		240,000		34,907
Other non-current liabilities		216		140		20
Deferred tax liabilities		5		—		—
Deferred revenue and customer deposits		330		—		—
Total non-current liabilities		60,551		240,140		34,927
Total liabilities		188,927		398,402		57,945

1	Organization and principal activities (continued)

The table sets forth the results of operations and cash flows of the VIE included in the company’s consolidated statements of comprehensive loss and cash flows.

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Revenues		70,148			284,348			709,594			103,206
Cost of revenues		(47,559	)		(206,789	)		(499,589	)		(72,662	)
Net income/(loss)		18,681			(40,003	)		(16,785	)		(2,441	)
Net cash used in operating activities		7,590			(51,016	)		(68,316	)		(9,936	)
Net cash used in investing activities		—			(10,000	)		(104,675	)		(15,224	)
Net cash provided by financing activities		1,000			—			154,901			22,529

There were no pledges or collateralization of the VIE’s assets as of December 31, 2017 and 2018. The amount of net liabilities of the VIE was RMB 18,874 and RMB 20,756 (US$3,019) as of December 31, 2017 and 2018, respectively. Creditors of the VIE have no recourse to the general credit of the primary beneficiary of the VIE, and such amounts have been parenthetically presented on the face of the consolidated balance sheets. The VIE holds certain assets, including data servers and related equipment for use in their operations. The VIE does not own any facilities except for the rental of certain office premises and data centers from third parties under operating lease arrangements. The VIE also holds certain value-added technology licenses, registered copyrights, trademarks and registered domain names, including the official website, which are also considered as revenue-producing assets. However, none of such assets was recorded on the Company’s consolidated balance sheets as such assets were all internally developed and expensed as incurred as they did not meet the capitalization criteria. The Company has not provided any financial or other support that it was not previously contractually required to provide to the VIE during the periods presented.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2	Summary of Significant Accounting Policies

Basis of presentation

The consolidated financial statements of the Company have been prepared in accordance with the generally accepted accounting principles of the United States (“U.S. GAAP”).

Principles of Consolidation

The consolidated financial statements include the financial statements of the Company, its subsidiaries, and the VIE. All significant intercompany transactions and balances have been eliminated upon consolidation.

Use of estimates

The preparation of the Company’s consolidated financial statements in conformity with U.S. GAAP requires the use of estimates and judgments that affect the reported amounts in the consolidated financial statements and accompanying notes. These estimates form the basis for judgments that management make about the carrying values of assets and liabilities, which are not readily apparent from other sources. Management base their estimates and judgments on historical information and on various other assumptions that they believe are reasonable under the circumstances. U.S. GAAP requires management to make estimates and judgments in several areas, including, but not limited to, those related to revenue recognition, collectability of accounts receivable, commitments, convertible notes, useful lives and impairment assessment of intangible assets, property and equipment, long-term investment, income taxes, valuation allowance for deferred tax assets, fair value change of derivative liability, and share-based compensation. These estimates are based on management's knowledge about current events and expectations about actions that the Company may undertake in the future. Actual results could differ from those estimates.

2	Summary of Significant Accounting Policies (continued)

Convenience translation

Translations of amounts from RMB into US$ for the convenience of the reader have been calculated at the exchange rate of RMB6.8755 per US$1.00 on December 31, 2018, as published on the website of the United States Federal Reserve Board. No representation is made that the RMB amounts could have been, or could be, converted into US$ at such rate.

Foreign currency translation

The functional currency of the Company and the Company’s subsidiary outside the PRC are US$. The Company’s PRC subsidiary and VIE adopted RMB as their functional currencies. The determination of the respective functional currency is based on the criteria stated in ASC 830, Foreign Currency Matters. The Company uses RMB as its reporting currency. The consolidated financial statements of the Company, are translated into RMB using the exchange rate as of the balance sheet date for assets and liabilities and average exchange rate for the year for income and expense items. Translation gains and losses are recorded in accumulated other comprehensive loss, as a component of shareholders’ deficit.

Transactions in currencies other than the functional currency are remeasured and recorded in the functional currency at the exchange rate prevailing on the transaction date.

Monetary assets and liabilities denominated in currencies other than the functional currency are remeasured into the functional currency at the rates of exchange prevailing at the balance sheet dates. Transaction gains and losses are recognized in the consolidated statements of comprehensive loss during the period or year in which they occur.

Cash and cash equivalents

Cash and cash equivalents primarily consist of cash and demand deposits which are highly liquid. The Company considers highly liquid investments that are readily convertible to known amounts of cash and with original maturities from the date of purchase of three months or less to be cash equivalents. All cash and cash equivalents are unrestricted as to withdrawal and use.

Restricted cash

Restricted cash represents cash granted by the government and designated only for the purchase of property and equipment for certain approved projects.

Accounts receivable and allowance for doubtful accounts

Accounts receivable are recorded at the realizable value amount, net of allowances for doubtful accounts. An allowance for doubtful accounts is recorded in the period when loss is probable based on many factors, including the age of the balance, the customer’s payment history and credit quality of the customers, current economic trends and other factors that may affect the Company’s ability to collect from customers. Bad debts are written off after all collection efforts have been exhausted.

Property and equipment, net

Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets or the remaining lease term, whichever is shorter. The estimated useful lives of property and equipment are as follows:


Computer equipment and servers		3 – 5 years
Office furniture and equipment		3 – 5 years
Leasehold improvements		over the shorter of lease terms or estimated useful lives of the assets

Expenditures for repair and maintenance are expensed as incurred. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation are removed from their respective accounts, and any gain or loss on such sale or disposal is reflected in the consolidated statements of comprehensive loss.

2	Summary of Significant Accounting Policies (continued)

Intangible assets

Intangible assets with finite lives are carried at cost less accumulated amortization. Intangible assets represent purchased computer software. All intangible assets with finite lives are amortized using the straight-line method over the estimated economic lives, which are as follows:

Computer software and systems

1 – 3 years

Impairment of long-lived assets other than goodwill

The Company evaluates long-lived assets, such as property and equipment and purchased intangible assets with finite lives, for impairment whenever events or changes in circumstances indicate the carrying value of an asset may not be recoverable in accordance with ASC 360, Property, Plant and Equipment. When such events occur, the Company assesses the recoverability of the asset group based on the undiscounted future cash flow the asset group is expected to generate and recognizes an impairment loss when estimated undiscounted future cash flow expected to result from the use of the asset group plus net proceeds expected from disposition of the asset group, if any, is less than the carrying value of the asset group. If the Company identifies an impairment, the Company reduces the carrying amount of the asset group to its estimated fair value based on a discounted cash flow approach or, when available and appropriate, to comparable market values. The Company uses estimates and judgments in its impairment tests and if different estimates or judgments had been utilized, the timing or the amount of any impairment charges could be different. No impairment loss was recognized for the years ended December 31, 2016, December 31, 2017 and 2018, respectively.

Long-term investments

In accordance with ASC 325-20, Investments-Other: Cost Method Investments, the Company carries at cost its investments in investees which do not have readily determinable fair value and the Company does not have significant influence. The Company only adjusts for other-than-temporary declines in fair value and distributions of earnings that exceed the Company’s share of earnings since its investment.

Management regularly evaluates the impairment of the cost method investments based on performance and financial position of the investee as well as other evidence of market value. Such evaluation includes, but is not limited to, reviewing the investee’s cash position, recent financing, projected and historical financial performance, cash flow forecasts and financing needs. An impairment loss is recognized in earnings equal to the excess of the investment’s cost over its fair value at the balance sheet date of the reporting period for which the assessment is made. The fair value would then become the new cost basis of investment.

Deferred revenue and customer deposits

Deferred revenue consists of payments from customers in advance of revenue recognition. Customer deposits relate to customer’s unused balances that are refundable. Once this balance is utilized by the customer, the corresponding amount would be recognized as revenue.

Convertible notes

At the commitment date, the fees and expenses associated with the issuance of the convertible notes are recorded as a discount to the debt liability in accordance with ASU 2015-03. The convertible notes, which is the proceeds net of fees and expenses payable to the creditor and the fair value of the bifurcated derivative, will be accreted to the redemption value on the maturity date using the effective interest method over the estimated life of the debt instrument.

The Company has early adopted ASU 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs, and ASU 2017-11, Accounting for Certain Financial Instruments with Down Round Features. ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. The issuance cost of RMB8,436 (US$1,227) was currently presented as a direct deduction from the principal amount of the Convertible Notes on the consolidated balance sheet as of December 31, 2018. ASU 2017-11 no longer requires the Company to consider down round features when determining whether its embedded Conversion Option is indexed to its own stock.

2	Summary of Significant Accounting Policies (continued)

Value added taxes (“VAT”)

The Company presents VAT assessed by government authorities as reductions of revenues. Pursuant to the PRC tax legislation, VAT is generally imposed in lieu of business tax in the modern service industries, on a nationwide basis. VAT of 6% applies to revenue derived from the provision of certain modern services. The Company is allowed to offset the qualified input VAT paid on taxable purchases against the output VAT chargeable on the modern services provided.

Share split

On March 1, 2017, the board of directors approved a 1 for 10 share split. Share and per share amounts for common shares and contingently redeemable convertible preferred shares disclosed for all prior periods have been retroactively adjusted to reflect the effects of the share split.

Treasury shares

Treasury shares represent shares repurchased by the Company that are no longer outstanding and are held by the Company. Treasury shares are accounted for under the cost method per ASC 505-30 Treasury Stock. Under this method, repurchase of shares were recorded as treasury shares at historical purchase price. On November 20, 2018, the Board of Directors of the Company approved a plan to repurchase its own issued and outstanding American depositary shares (“ADSs”) up to an aggregate value of US$10 million from the open market (the “Repurchase Plan”). As of December 31, 2018, under the Repurchase Plan, the Company had repurchased an aggregate of 69,455 ADSs, representing 46,303 Class A common shares on the open market for a total cash consideration of US$468.

2	Summary of Significant Accounting Policies (continued)

Revenue recognition

The Company recognizes revenue once all of the following criteria have been met: (1) persuasive evidence of an arrangement exists; (2) services have been provided; (3) the price is fixed or determinable; and (4) collectability is reasonably assured.

Data solutions

The Company generates data solutions revenues primarily by creating and delivering targeted marketing and other vertical data solutions. Targeted marketing revenue is generated by the Company providing an integrated marketing campaign to advertisers mainly through the Company’s Xiaoguotong marketing platform, which is built upon the Company’s multi-dimensional mobile device dataset. The Company generally will create, design, develop and optimize the advertising content for its advertisers. The advertisements are displayed on a wide spectrum of reputable publishers, through bidding for advertisement slots using rates directly negotiated with the various publishers.

The arrangements with advertisers are evidenced through contractual agreements that stipulate the types of advertising to be delivered, the timing and the pricing. Advertisers pay for targeted advertisements based on the number of clicks and downloads taken by the users. Revenue is recognized in the period in which the user performs the action the advertiser contracted the Company for.

The Company recognizes revenue on a gross basis as the primary obligor, as it uses its own platform’s mobile device dataset with its comprehensive demographic targeting ability to accurately pinpoint the specific mobile devices that is most suitable for the customer’s ads. Additionally, the Company has pricing latitude, has discretion in selecting publishers whose advertisement slots will be purchased, is highly involved in the determination of service specifications and bears credit risk. Based on the advertiser’s preference to avoid lower quality publishers, the Company may recommend a specific reputable online media network to certain advertisers. After pinpointing the specific mobile devices that are most suitable for the customer’s ads using its mobile device dataset, it bids for the available advertising slots on the network and then places the advertisement.

Developer services

The Company enters into agreements with its customers to provide push notification and instant messaging (collectively “notification services”). Under the terms of the contractual agreements of notification services, the Company provides its customers with access to its notification services platform over the specified period. This enables customers to send notifications and messages to users. Revenue from notification services is recognized using a specific performance method.

Costs of revenues

Cost of revenues consists primarily of depreciation, labor, bandwidth costs and purchasing of advertising inventory. The Company incurs various sales tax and surcharges such as, city construction tax and education surcharges and cultural development fee in connection with the services provided. In accordance with ASC subtopic 605-45, Revenue Recognition, Principal Agent Considerations (“ASC 605-45”), the Company includes the sales tax and surcharges incurred in cost of revenues.

Research and development

Research and development expenses are primarily incurred in the development of new services, new features, and general improvement of the Company’s technology infrastructure to support its business operations. Research and development costs are expensed as incurred unless such costs qualify for capitalization as software development costs. In order to qualify for capitalization, (i) the preliminary project should be completed, (ii) management has committed to funding the project and it is probable that the project will be completed and the software will be used to perform the function intended, and (iii) it will result in significant additional functionality in the Company’s services. No research and development costs were capitalized during any of the years presented as the Company has not met all of the necessary capitalization requirements.

Advertising expense

Advertising expenses, including promotion expenses, are charged to “sales and marketing expenses” as incurred. Advertising expenses amounted to RMB10,377, RMB5,277 and RMB6,697 (US$974) for the year ended December 31, 2016, 2017 and 2018, respectively.

2	Summary of Significant Accounting Policies (continued)

Other income

Other income represents government grants and profit sharing program with Depositary Bank related to ADSs depositary. Government grants are recognized when there is reasonable assurance that the Company will comply with the attached conditions. When the grant relates to an expense item, it is recognized on a systemic basis in the consolidated statement of comprehensive loss over the period necessary to match the grant to the related costs. Where the grant relates to an asset acquisition, it is recognized in the consolidated statements of comprehensive loss in proportion to the depreciation of the related assets. Profit sharing program is recognized over five-year period as specified in the contract based on certain parameters.

Government grants

Government grants primarily consist of financial grants received from provincial and local governments for operating a business in their jurisdictions and compliance with specific policies promoted by the local governments. For certain government grants, there are no defined rules and regulations to govern the criteria necessary for companies to receive such benefits, and the amount of financial subsidy is determined at the discretion of the relevant government authorities. The government grants of non-operating nature with no further conditions to be met are recorded as non-operating income in “Other income, net” when received. The government grants with certain operating conditions are recorded as “deferred income” when received and will be recorded as operating income when the conditions are met.

Operating leases

Leases where substantially all the risks and rewards of ownership of assets remain with the lessor are accounted for as operating leases. Rentals applicable to such operating leases are recognized on a straight-line basis over the lease term. The Company had no capital leases during the years presented.

Employee defined contribution plan

Full time employees of the Company in the PRC participate in a government mandated defined contribution plan pursuant to which certain pension benefits, medical care, unemployment insurance, employee housing fund, and other welfare benefits are provided to employees. Chinese labor regulations require that the Company make contributions to the government for these benefits based on a certain percentage of the employee’s salaries. The Company has no legal obligation for the benefits beyond the contributions. The total amount that was expensed as incurred was RMB5,455, RMB12,121 and RMB11,301 (US$1,644) for the year ended December 31,2016, December 31, 2017 and 2018, respectively.

Income taxes

The Company accounts for income taxes using the liability approach and recognizes deferred tax assets and liabilities for the expected future consequences of events that have been recognized in the consolidated financial statements or in the Company’s tax returns. Deferred tax assets and liabilities are recognized on the basis of the temporary differences that exist between the tax basis of assets and liabilities and their reported amounts in the consolidated financial statements using enacted tax rates in effect for the year end in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in earnings. Deferred tax assets are reduced by a valuation allowance through a charge to income tax expense when, in the opinion of management, it is more-likely-than-not that a portion of or all of the deferred tax assets will not be realized. The Company evaluates the potential for recovery of deferred tax assets by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. The components of the deferred tax assets and liabilities are classified as non-current.

The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of the benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained (defined as a likelihood of more than fifty percent of being sustained upon an audit, based on the technical merits of the tax position), the tax position is then assessed to determine the amount of benefits to recognize in the consolidated financial statements. The amount of the benefits that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. Interest and penalties on income taxes will be classified as a component of the provisions for income taxes.

2	Summary of Significant Accounting Policies (continued)

Income taxes (continued)

The Company evaluated its income tax uncertainty under ASC 740. ASC 740 clarifies the accounting for uncertainty in income taxes by prescribing the recognition threshold a tax position is required to meet before being recognized in the financial statements. The Company elects to classify interest and penalties related to an uncertain tax position, if and when required, as part of income tax expense in the consolidated statements of comprehensive loss.

The Company did not recognize any income tax due to uncertain tax position or incur any interest and penalties related to potential underpaid income tax expenses during the years presented.

Share-based compensation

In accordance with ASC 718, Compensation-Stock Compensation, the Company determines whether an award granted to its employees should be classified and accounted for as a liability award or equity award. The Company’s share-based compensation to its employees which were classified as equity awards were recognized in the consolidated statements of comprehensive loss based on the grant date fair value. The Company’s share-based compensation to its employees which were classified as liability awards were recognized in the consolidated statements of comprehensive loss based on the fair value at each reporting date until settlement. The Company early adopted Accounting Standard Update (“ASU”) ASU 2016-09—Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting and elected to account for forfeitures as they occur.

Fair value measurements

Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Company considers the principal or most advantageous market in which it would transact and the market-based risk measurement or assumptions that market participants would use when pricing the asset or liability.

Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1-Quoted prices in active markets for identical assets or liabilities.

Level 2-Observable inputs other than quoted prices in active markets, quoted prices for identical or similar assets and liabilities in inactive markets or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3-Inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.

The carrying amounts of financial assets and liabilities, such as cash equivalents, restricted cash, accounts receivable, other receivables within prepaid expenses and other current assets, balances with related parties, accounts payable, and other payables with accrued liabilities and other current liabilities, approximate their fair values because of the short maturity of these instruments. The carrying amounts of restricted cash (non-current) approximate its fair value since it bears interest rates which approximate market interest rates.

Comprehensive loss

Comprehensive loss is defined as the increase or decrease in equity of the Company during a year from transactions and other events and circumstances excluding transactions resulting from investments by owners and distributions to owners. Accumulated other comprehensive loss of the Company includes the foreign currency translation adjustments.

2	Summary of Significant Accounting Policies (continued)

Loss per share

In accordance with ASC 260, Earning per Share, basic loss per share is computed by dividing net loss attributable to common shareholders by the weighted average number of common shares outstanding during the period using the two-class method. Under the two-class method, net income is allocated between common shares based on dividends declared (or accumulated) and participating rights in undistributed earnings as if all the earnings for the reporting period had been distributed. For the year ended December 31, 2018, the two-class method is applicable because the Company has two classes of common shares outstanding, Class A and Class B common shares, respectively. The participating rights (liquidation and dividend rights) of the holders of the Company’s Class A and Class B common shares are identical, except with respect to voting. As a result, and in accordance with ASC 260, as the liquidation and dividend rights are identical, the undistributed loss is allocated on a proportionate basis.

Diluted loss per share is computed by dividing net loss attributable to common shareholders as adjusted for the effect of dilutive common equivalent shares, if any, by the weighted average number of common and dilutive common equivalent shares outstanding during the years. Common equivalent shares consist of the common shares issuable upon the conversion of the Company’s contingently redeemable convertible preferred shares and the convertible senior notes using the if-converted method and common shares, including partially paid shares, issuable upon the exercise of the share options, using the treasury stock method. Common share equivalents are excluded from the computation of diluted loss per share if their effects would be anti-dilutive.

Concentration of risks

Concentration of credit risk

Financial assets that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, short-term investments and accounts receivable.

The Company places its cash and cash equivalents with reputable financial institutions which have high-credit ratings. As of December 31, 2017 and 2018, the aggregate amount of cash and cash equivalents and restricted cash of RMB82,609 and RMB331,374 (US$48,198), respectively, were held at major financial institutions located in the PRC, and US$19,232 and US$35,678 (RMB245,303), respectively, were deposited with major financial institutions located outside the PRC. There has been no recent history of default related to these financial institutions. The Company continues to monitor the financial strength of the financial institutions. The Company manages credit risk of accounts receivable through ongoing monitoring of the outstanding balances.

Concentration of suppliers

Approximately 81.3% and 50.9% of advertising costs were paid to three suppliers for the year ended December 31, 2017 and 2018, respectively.

Business and economic risk

The Company believes that changes in any of the following areas could have a material adverse effect on the Company’s future consolidated financial position, results of operations or cash flows; changes in the overall demand for services; competitive pressures due to new entrants; advances and new trends in new technologies and industry standards; changes in certain strategic relationships; regulatory considerations and risks associated with the Company’s ability to attract employees necessary to support its growth. The Company’s operations could also be adversely affected by significant political, regulatory, economic and social uncertainties in the PRC.

Currency convertibility risk

Substantially all of the Company’s businesses are transacted in RMB, which is not freely convertible into foreign currencies. All foreign exchange transactions take place either through the People’s Bank of China (“PBOC”) or other authorized financial institution at exchange rates quoted by PBOC. Approval of foreign currency payments by the PBOC or other regulatory institutions requires submitting a payment application form together with suppliers’ invoices and signed contracts.

Foreign currency exchange rate risk

The functional currency and the reporting currency of the Company are the US$ and the RMB, respectively. On June 19, 2010, the PBOC announced the end of the RMB’s de facto peg to the US$, a policy which was instituted in late 2008 in the face of the global financial crisis, to further reform the RMB exchange rate regime and to enhance the RMB’s exchange rate flexibility. On March 15, 2014, the People’s Bank of China announced the widening of the daily trading band for RMB against US$. The appreciation of the US$ against RMB was approximately 4.79% in 2018. Most of the Company’s revenues and costs are denominated in RMB, while a portion of cash and cash equivalents, short-term investments, and accounts payable are denominated in US$. Any significant revaluation of RMB may materially and adversely affect the Company’s consolidated revenues, earnings and financial position in US$.

2	Summary of Significant Accounting Policies (continued)

Segment information

The Company’s chief operating decision maker is the Chief Executive Officer, who makes resource allocation decisions and assesses performance based on the consolidated financial results. As a result, the Company has only one reportable segment.

As the Company generates substantially most of its revenues in the PRC, no geographical segments is presented.

Recently issued accounting pronouncements

As a company with less than US$1.07 billion in revenue for the last fiscal year, the company qualifies as an “emerging growth company” pursuant to the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). An emerging growth company may take advantage of specified reduced reporting and other requirements that are otherwise applicable generally to public companies. These provisions include a provision that an emerging growth company does not need to comply with any new or revised financial accounting standards until such date that a private company is otherwise required to comply with such new or revised accounting standards. The Company will take advantage of the extended transition period.

In May 2014, the Financial Accounting Standard Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606). The guidance substantially converges final standards on revenue recognition between the FASB and the International Accounting Standards Board providing a framework on addressing revenue recognition issues and, upon its effective date, replaces almost all existing revenue recognition guidance, including industry-specific guidance, in current U.S. GAAP.

The core principle of the guidance is that an entity should recognize revenues to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve this core principle, an entity should apply the following steps:

Step 1: Identify the contract(s) with a customer.

Step 2: Identify the performance obligations in the contract.

Step 3: Determine the transaction price.

Step 4: Allocate the transaction price to the performance obligations in the contract.

Step 5: Recognize revenue when (or as) the entity satisfies a performance obligation.

In August 2015, the FASB issued its final standard formally amending the effective date of the new revenue recognition guidance. The amendments in this ASU are effective for annual reporting periods beginning after December 15, 2018, including interim periods beginning after January 1, 2020. As an “emerging growth company,” or EGC, the Company has elected to take advantage of the extended transition period provided in the Securities Act Section 7(a)(2)(B) for complying with new or revised accounting standards applicable to private companies. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customer - Principal versus Agent Considerations (“ASU 2016-08”), which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, Revenue from Contracts with Customer - Identifying Performance Obligations and Licensing, which clarifies guidance related to identifying performance obligations and licensing implementation guidance contained in ASU 2014-09. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers - Narrow-Scope Improvements and Practical Expedients (“ASU 2016-12”), which addresses narrow-scope improvements to the guidance on collectability, non-cash consideration and completed contracts at transition and provides practical expedients for contract modifications at transition and an accounting policy election related to the presentation of sales taxes and other similar taxes collected from customers. The effective dates for these amendments are the same as the effective date of ASU 2014-09. Early adoption is permitted.

The Company will adopt ASU 2014-09 for the annual reporting periods beginning January 1, 2019, using the modified retrospective method. The cumulative effect of initially applying the new standard will be recognized on the day of initial application and prior periods will not be retrospectively adjusted. The Company’s implementation efforts are substantially complete. The Company also estimate that there will not be a material impact to the beginning balance of retained earnings.

2	Summary of Significant Accounting Policies (continued)

Recently issued accounting pronouncements (continued)

In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall (Subtopic 825-10). The amendments require all equity investments to be measured at fair value with changes in the fair value recognized through net income (other than those accounted for under equity method of accounting or those that result in consolidation of the investee). The amendments also require an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instruments-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. In addition, the amendments in this ASU eliminate the requirement to disclose the fair value of financial instruments measured at amortized cost for entities that are not public business entities. The amendments in this ASU are effective for annual reporting periods beginning after December 15, 2018, including interim periods after December 15, 2019. The Company is in the process of evaluating the impact of the adoption of this guidance on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This ASU modifies existing guidance for off-balance sheet treatment of a lessees’ operating leases by requiring lessees to recognize lease assets and lease liabilities, whilst, lessor accounting is largely unchanged. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), which provides another transition method in addition to the existing transition method by allowing entities to initially apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption consistent with preparers’ requests. The amendments in this Update are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years for public entities. The Company is in the process of evaluating the impact of adoption of this guidance on its consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). This ASU is intended to improve financial reporting by requiring timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. This ASU requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. This ASU requires enhanced disclosures to help investors and other financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of the Company’s portfolio. These disclosures include qualitative and quantitative requirements that provide additional information about the amounts recorded in the financial statements. The amendments in this ASU are effective for fiscal years beginning after December 15, 2020, including interim periods within fiscal years beginning after December 15, 2021. In November 2018, the FASB issued ASU No. 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses (“ASU 2018-19”), which amends ASU 2016-13 to clarify that receivables arising from operating leases are not within the scope of Subtopic 326-20, and instead, impairment of such receivables should be accounted for in accordance with Topic 842, Leases. ASU 2016-13 and ASU 2018-19 are effective for fiscal years and interim periods within those years beginning after December 15, 2019, with early adoption permitted as of the fiscal years beginning after December 15, 2018. An entity will apply the amendments in these updates through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (that is, a modified-retrospective approach). The Company is currently evaluating the impact this guidance will have on its consolidated financial statements when adopted. The Company is in the process of evaluating the impact of adoption of this guidance on its consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This ASU reduces the existing diversity in practice in financial reporting across all industries by clarifying certain existing principles in ASC 230, Statement of Cash Flows (“ASC 230”), including providing additional guidance on how and what an entity should consider in determining the classification of certain cash flows. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. The Company has early adopted this standard.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. This ASU requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This ASU does not provide a definition of restricted cash or restricted cash equivalents. The amendments are effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. The Company has early adopted this standard.

2	Summary of Significant Accounting Policies (continued)

Recently issued accounting pronouncements (continued)

In February 2017, the FASB issued ASU No. 2017-05, Other income—Gains and Losses from the Derecognition of Nonfinancial Assets, which clarifies that a financial asset is within the scope of Subtopic 610-20 if it meets the definition of an in substance nonfinancial asset. The amendments in this update also clarify that nonfinancial assets within the scope of Subtopic 610-20 may include nonfinancial assets transferred within a legal entity to a counterparty. This standard is effective for annual reporting periods beginning after December 15, 2018, and interim periods within annual periods beginning after December 15, 2019. The Company is in the process of evaluating the impact of adoption of this guidance on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is in the process of evaluating the impact of adoption of this guidance on its consolidated financial statements.

Accounts Receivable, Net

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts receivable, net

3	Accounts receivable, net

	As of December 31,
	2017			2018
	RMB			RMB			US$
Accounts receivable		53,056			151,219			21,994
Less: allowance for doubtful accounts		(3,462	)		(9,308	)		(1,354	)
Total accounts receivable, net		49,594			141,911			20,640

The following table presents the movement in the allowance for doubtful accounts:

	As of December 31,
	2017		2018
	RMB		RMB			US$
Balance at beginning of year		1,035		3,462			504
Provisions		2,427		6,389			929
Write-offs		—		(543	)		(79	)
Balance at end of year		3,462		9,308			1,354

Prepayment and Other Current Assets

12 Months Ended

Dec. 31, 2018

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Prepayment and other current assets

4	Prepayment and other current assets

Prepayment and other current assets consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Prepaid media cost		19,610		54,937		7,990
Prepaid service fee		1,762		6,804		989
Others		12,856		18,837		2,740
Total prepayment and other current assets		34,228		80,578		11,719

Property and Equipment, Net

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and equipment, net

5	Property and equipment, net

Property and equipment consist of the following:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Office furniture and equipment		2,647			4,920			716
Computer equipment and servers		63,326			111,274			16,184
Leasehold improvements		789			7,256			1,055
Less: Accumulated depreciation		(13,739	)		(30,576	)		(4,447	)
Total property and equipment, net		53,023			92,874			13,508

No impairment charges were recognized on fixed assets for the year ended December 31, 2016, 2017 and 2018, respectively.

Depreciation expense recognized for the years ended December 31, 2016, 2017 and 2018 were RMB3,433, RMB8,805 and RMB18,084 (US$2,630), respectively.

Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible assets

6	Intangible assets

Intangible assets consist of the following:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Computer software and systems		319			1,874			273
Less: Accumulated amortization		(36	)		(343	)		(50	)
Total intangible assets, net		283			1,531			223

No impairment charges were recognized on intangible assets for the years ended December 31, 2016, 2017 and 2018, respectively.

Amortization expense of intangible assets were RMB nil, RMB35 and RMB307 (US$45), for the years ended December 31, 2016, 2017 and 2018 respectively.

Estimated amortization expense relating to the existing intangible assets with finite lives for each of the next five years is as follows:

	RMB		US$
For the year ending December 31, 2019		749		109
2020		464		67
2021		318		47
2022		—		—
2023		—		—

No intangible assets with an indefinite useful life as of December 31, 2017 and 2018.

Long-Term Investments

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Long-Term Investments

7	Long-term investments

As of December 31, 2017 and 2018, long-term investments consisted of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Cost method investments		10,980		79,696		11,591
Less: Impairment loss		—		—		—
Total		10,980		79,696		11,591

In 2018, the Company acquired 5.93% of the share capital of Zhuoxuan, a non-listed company, for RMB5,438 (US$792). The investment in Zhuoxuan was classified as a cost method investment, as the Company does not have significant influence over Zhuoxuan and because there is no readily determinable fair value.

In 2018, the Company acquired 13.8% of the share capital of Mengxiang, a non-listed company, for RMB21,512 (US$3,134). The investment in Mengxiang was classified as a cost method investment, as the Company does not have significant influence over Mengxiang and because there is no readily determinable fair value.

In 2018, the Company acquired 10.0% of the share capital of Qianhai, a non-listed company, for RMB40,000 (US$5,828). The investment in Qianhai was classified as a cost method investment, as the Company does not have significant influence over Qianhai and because there is no readily determinable fair value.

In 2016, the Company has acquired a call option to purchase preferred shares of Skymind in a future financing round for RMB980 (US$150). In 2018, the Company held 1.19% of the share capital of Skymind with the exercise of call option and RMB1,716 (US$250). The investment in Skymind was classified as a cost method investment, as the Company does not have significant influence over Skymind and because there is no readily determinable fair value.

In 2017, the Company acquired 6.25% of the share capital of Shuwei, a non-listed company, for RMB10,000 (US$1,457), and the Company’s ownership of share in Shuwei decrease to 4.27% in 2018 due to Shuwei’s subsequent rounds of financing. The investment in Shuwei was classified as a cost method investment, as the Company does not have significant influence over Shuwei and because there is no readily determinable fair value.

There were no impairment indicators for the cost method investment and no impairment losses for the three years ended December 31, 2016, 2017 and 2018.

Deferred Revenue and Customer Deposits

12 Months Ended

Dec. 31, 2018

Revenue Recognition And Deferred Revenue [Abstract]

Deferred Revenue and Customer Deposits

8	Deferred revenue and customer deposits

Deferred revenue and customer deposits consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Deferred revenue		28,921		33,067		4,809
Customer deposits		20,636		26,416		3,842
Total deferred revenue and customer deposits — current		49,557		59,483		8,651
Deferred revenue — non-current		330		10,265		1,493

8	Deferred revenue and customer deposits (continued)

Roll-forward of customers deposits:

	Year ended December 31,
	2017			2018
	RMB			RMB			US$
Balance at beginning of year		6,064			20,636			3,001
Cash received from customers during the year		129,555			407,630			59,287
Revenue recognized during the year		(112,770	)		(397,488	)		(57,812	)
Refunds paid during the year		(2,213	)		(4,362	)		(634	)
Balance at end of year		20,636			26,416			3,842

Accrued Liabilities and Other Current Liabilities

12 Months Ended

Dec. 31, 2018

Payables And Accruals [Abstract]

Accrued liabilities and other current liabilities

9	Accrued liabilities and other current liabilities

Accrued liabilities and other current liabilities consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Accrued payroll and welfare payables		38,704		51,607		7,506
Other taxes and surcharge		2,676		11,277		1,640
Service fees		560		11,130		1,619
Acquisition of fixed assets		9,731		104		15
Others		968		2,548		371
Total accrued liabilities and other current liabilities		52,639		76,666		11,151

Contingently Redeemable Convertible Preferred Shares

12 Months Ended

Dec. 31, 2018

Temporary Equity [Abstract]

Contingently Redeemable Convertible Preferred Shares

10	Contingently redeemable convertible preferred shares

Series A contingently redeemable convertible preferred shares (“Series A preferred shares”)

On November 18, 2014, the Company issued Series A-1 contingently redeemable convertible preferred shares (“Series A-1 preferred shares”) of 5,187,780 and 367,780 to IDG-Accel China Growth Fund III L.P and IDG-Accel China III Investors L.P, respectively, at US$0.36 per share for a total consideration of US$2,000.

On January 21, 2015, the Company issued Series A-2 contingently redeemable convertible preferred shares (“Series A-2 preferred shares”) of 1,388,890, 1,388,890, 2,593,890 and 183,890 to Elite Bright

International Limited, Mandra iBase Limited, IDG-Accel China Growth Fund III L.P and IDG-Accel China III Investors L.P, respectively, at US$0.36 per share for a total consideration of US$2,000.

Series B contingently redeemable convertible preferred shares (“Series B preferred shares”)

On May 13, 2015, the Company issued Series B contingently redeemable convertible preferred shares (“Series B preferred shares”) of 529,100, 529,100, 494,070, 35,030 and 6,349,210 to Elite Bright International Limited, Mandra iBase Limited, IDG-Accel China Growth Fund III L.P, IDG-Accel China III Investors L.P and Greatest Investments Limited, respectively, at US$0.95 per share for a total consideration of US$7,500.

Series C contingently redeemable convertible preferred shares (“Series C preferred shares”)

On April 1, 2016, the Company issued Series C-1 contingently redeemable convertible preferred shares (“Series C-1 preferred shares”) of 235,160 and 2,116,400 to Greatest Investments Limited and Shenzhen Guohai Chuangxin Investment Management Limited Corporation, respectively, at US$4.73 for a total consideration of US$11,111.

10	Contingently redeemable convertible preferred shares (continued)

On October 31, 2016, the Company issued Series C-2 contingently redeemable convertible preferred shares (“Series C-2 preferred shares”) of 634,920, 1,693,120 and 211,640 to Mandra iBase Limited, T.C.L. Industries Holdings (H.K.) Ltd and Genesis Ventures Limited, respectively, at US$4.73 per share for a total consideration of US$12,000.

Series D contingently redeemable convertible preferred shares (“Series D preferred shares”)

On October 5, 2017, the Company issued Series D contingently redeemable convertible preferred shares of 28,062, 2,441,572 and 3,089,853 to Fidelity Investment Funds, Fidelity China Special Situations PLC and Fidelity Funds, respectively, at US$5.40 per share for a total consideration of US$30,000.

Dividend rights

Each holder of the Series A, B, C, D preferred shares (collectively “Preferred Shares”) will be entitled to receive non-cumulative dividends, prior and in preference to holders of common shares, when declared by the Board of Directors. After payment of the preferential dividends relating to the Preferred Shares have been paid in full, each holder of the Preferred Shares will be entitled to receive dividends payable out of any remaining funds that are legally available when declared by the Board of Directors.

For the periods presented, no dividends were declared by the Company’s Board of Directors on the Preferred Shares.

Voting rights

Each holder of the Preferred Shares are entitled to the number of votes equal to the number of common shares into which such Preferred Shares could be converted at the voting date. Preferred shareholders will vote together with common shareholders, and not as a separate class of series, on all matters put before the shareholders.

Liquidation preference

In the event of any liquidation, dissolution or winding up of the Company or any deemed liquidation event defined as (i) the liquidation, dissolution or winding-up of the Company, (ii) the acquisition of the Company (whether by a sale of equity, merger or consolidation) in which in excess of 50% of such Company’s voting power outstanding before such transaction is transferred; (iii) the change of the control right of any Company; or (iv) the sale, lease, transfer or other disposition of all or substantially all of the assets of any Company or the exclusive licensing of substantially all of the Company’s intellectual properties, the assets or surplus funds of the Company available for distribution will be distributed as follows:

The holders of Series D preferred shares are entitled to receive an amount equal to 115% of the Series D Issue Price, plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series C, B and A preferred shares and the common shareholders of the Company.

After the payment to the holders of Series D preferred shares, the holders of Series C preferred shares are entitled to receive an amount equal to 100% of the Issue Price, plus an annual simple return of 10% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series B and A preferred shares and the common shareholders of the Company.

After the payment to the holders of Series C preferred shares, the holders of Series B preferred shares are entitled to receive an amount equal to 125% of the Series B Issue Price, plus an annual compounded return of 6% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series A preferred shares and the common shareholders of the Company.

After the payment to the holders of Series B preferred shares, the holders of Series A preferred shares are entitled to receive an amount equal to 150% of the Series A Issue Price, plus an annual compounded return of 8% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the common shareholders of the Company.

10	Contingently redeemable convertible preferred shares (continued)

After payment has been made to the holders of the Preferred Shares in accordance with the above, the remaining assets of the Company available for distribution to shareholders shall be distributed ratably among the holders of common shares and Preferred Shares based on the number of common shares into which such Preferred Shares are convertible.

Conversion rights

Each holder of the Preferred Share has the right, at the sole discretion of the holder, to convert at any time and from time to time, all or any portion of the Preferred Shares into common shares based on the then-effective Conversion Price.

The initial conversion price is the stated issuance price for each series of Preferred Shares. The initial conversion ratio is on a one for one basis and subject to adjustments in the event that the Company issues additional common shares through options or convertible instruments for a consideration per share received by the Company less than the original respective conversion prices, as the case may be, in effect on the date of and immediately prior to such issue. In such event, the respective conversion price is reduced, concurrently with such issue, to a price as adjusted according to an agreed-upon formula. The above conversion prices are also subject to adjustments on a proportional basis upon other dilution events.

The Company’s Series C preferred share agreement contained a “Performance Ratchet” whereby if the Company’s PRC GAAP audited revenue was less than (i) RMB80,000 in 2016, or (ii) RMB120,000 in 2017, Weidong Luo and the Company shall compensate the Series C investors in accordance to the specified formula.

In the event of a qualified IPO, each Preferred Share will automatically be converted into common shares.

Redemption right

If the Company shall at any time after the earlier of (i) January 1, 2020 or (ii) the date that is twelve months after the closing of the IPO, receive a written request from the holders of at least 50% or more of the issued and outstanding Preferred Shares (or common shares issued upon the conversion of the Preferred Shares) or Mandra iBased Limited may request in writing that the Company effect a registration for at least 20% of their Registrable Securities on any internationally recognized exchange that is reasonably acceptable to such requesting Preferred Shares and Common Shareholders using its best efforts.

Furthermore, if the Company qualifies for registration on Form F-3 or Form S-3 (or any comparable form for Registration in a jurisdiction other than the United States), any Preferred Share holder may request the Company to file, in any jurisdiction in which the Company has had a registered underwritten public offering, a Registration Statement on Form F-3 or Form S-3 (or any comparable form for Registration in a jurisdiction other than the United States) using its best efforts.

Redemption of preferred shares

On April 11, 2018, the Company redeemed the 1,738,720 Series C preferred shares held by T.C.L. Industries Holdings (H.K.) Ltd. for an aggregate price of US$9,049. The Company accounted for the difference between the fair value of the consideration paid for the repurchase preferred shares and the carrying value of the preferred shares as an increase to the net loss attributable to ordinary shareholders in the statement of comprehensive loss.

Initial measurement and subsequent accounting for Preferred Shares

The Preferred Shares do not meet the criteria of mandatorily redeemable financial instruments specified in ASC 480-10-S99, and have been classified as mezzanine equity in the consolidated balance sheets as these Preferred Shares are contingently redeemable upon the occurrence of a conditional event (i.e. Deemed Liquidation Event).

The Preferred Shares were initially measured at fair value. Beneficial conversion features exist when the conversion price of the Preferred Shares is lower than the fair value of the common shares at the commitment date, which is the issuance date in the Company’s case. When a beneficial conversion feature exists as of the commitment date, its intrinsic value is bifurcated from the carrying value of the Preferred Shares as a contribution to additional paid-in capital. On the respective commitment dates, the most favorable conversion price used to measure the beneficial conversion feature of the Preferred Shares were higher than the fair value per common share and therefore no beneficial conversion feature was recognized. The Company determined the fair value of common shares with the assistance of an independent third party valuation firm.

10	Contingently redeemable convertible preferred shares (continued)

Based on the Company’s 2016 PRC GAAP audited financial statements, the “Performance Ratchet” has not been triggered, Weidong Luo and the Company are not required to compensate the Series C holders.

In determining whether to account for an amendment of equity-classified preferred shares as a modification or extinguishment, the Company considers an amendment that results in a greater than 10% change in fair value based on an analysis similar to ASC 470-50 is an extinguishment. An amendment that does not meet this criterion is a modification. The amendment in the redemption dates of Series A and Series B preferred shares at the issuance of Series C preferred shares and the removal of the revenue target for the Series A, Series B and Series C preferred shares at issuance of Series D preferred shares, resulted in a modification (as the amendment did not result in a greater than 10 percent change in cash flows) with no further accounting impact as the modification did not result in a change in the fair value of the related preferred shares.

The Company has elected to accrete the preferred shares to their redemption value over the contractual period since issuance to the earliest redemption date using the effective interest rate method. The accretion to redemption value including cumulative dividends shall be recorded as a reduction of income available to common shareholders in accordance with ASC 480-10-S99 3A.

The Preferred Shares were converted to common shares immediately upon the completion of the Company’s IPO on July 26, 2018.

The movement in the carrying value of the convertible preferred shares is as follows:

Mezzanine equity	Series A			Series B			Series C			Series D			Total
	RMB			RMB			RMB			RMB			RMB
Balance as of December 31, 2016		26,804			52,044			141,691			—			220,539
Issuance of Series C preferred shares		—			—			20,571			—			20,571
Issuance of Series D preferred shares		—			—			—			206,359			206,359
Issuance cost of Series D preferred shares		—			—			—			(7,223	)		(7,223	)
Accretion of Preferred Shares		175			679			6,055			19,482			26,391
Balance as of December 31, 2017		26,979			52,723			168,317			218,618			466,637
Accretion of Preferred Shares		1,463			4,137			7,441			11,053			24,094
Redemption of Preferred Shares		—			—			(57,234	)		—			(57,234	)
Conversion of Preferred Shares		(28,442	)		(56,860	)		(118,524	)		(229,671	)		(433,497	)
Balance as of December 31, 2018		—			—			—			—			—
Balance as of December 31, 2018 (US$)		—			—			—			—			—

Share-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation

11	Share-based compensation

Share option plans

2014 Incentive Plan

On July 23 2014, the Company’s board of directors and shareholders approved the 2014 Incentive Plan (the “2014 Plan”). Awards under the 2014 Plan vest to 4 years from the date of grant and expire no more than 10 years after the grant date. The Company reserved a total of 5,500,000 common shares for issuance under the 2014 Plan. As of December 31, 2018, 2,420 remains available for grant under the 2014 Plan.

2017 Incentive Plan

On March 1, 2017, the Company’s board of directors and shareholders approved the 2017 Incentive Plan (the “2017 Plan”). Awards under the 2017 Plan vest to 4 years from the date of grant and expire no more than 10 years after the grant date. The Company reserved a total of 6,015,137 common shares for issuance under the 2017 Plan. As of December 31, 2018, 3,467,708 shares remain available of grant under the 2017 Plan.

11Share-based compensation (continued)

The exercise price, vesting and other conditions of individual awards are determined by the board of directors or any of the committees appointed by the board of directors to administer the 2014 and 2017 Plans. The awards are subject to multiple service vesting periods arranging from 1 to 4 years, and will expire 10 years after the date of award. Upon the termination of the Grantee’s Continuous Service, the Company has the right to repurchase the vested award or shares obtained.

Share options

The following table summarizes the share option activity for the year ended December 31, 2018:

Options Granted to Employees and Directors	Number of Options		Weighted- Average Exercise Price		Weighted- Average grant-date Fair Value per Option		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
			RMB		RMB				RMB
Outstanding, December 31, 2016		5,472,031		2.32		2.13		7.89		34,255
Granted		894,115		16.29		10.34		—		—
Forfeited		—		—		—		—		—
Expired		—		—		—		—		—
Exercised		—		—		—		—		—
Cancelled		—		—		—		—		—
Outstanding, December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Vested and expected to vest at December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Outstanding, December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Granted		1,736,390		26.68		45.72		—		—
Forfeited		55,520		26.55		24.69		—		—
Expired		—		—		—		—		—
Exercised		—	—		—		—		—
Cancelled		14,558		6.56		1.87		—		—
Outstanding, December 31, 2018		8,032,458		9.04		12.48		7.47		507,876
Vested and expected to vest at December 31, 2018		8,032,458		9.04		12.48		7.47		507,876
Exercisable at December 31, 2018		5,185,893		2.75		3.09		6.73		360,505

The aggregate fair value of options vested and recognized as expenses as of December 31, 2016, 2017 and 2018 were RMB2,703, RMB8,275 and RMB24,561 (US$3,572), respectively.

The aggregate unrecognized share-based compensation expense was RMB64,099 (US$9,323) as of December 31,2018, which the Company expects to recognize over an estimated weighted-average period of three to four years.

The Company estimates the fair value of each award on grant date using the binomial option pricing model with the assistance of an independent third-party valuation firm. The binominal model requires the input of highly subjective assumptions, including the expected share price volatility and the suboptimal early exercise factor. For expected volatility, the Company has made reference to historical volatilities of several comparable companies. The suboptimal early exercise factor was estimated based on the Company’s expectation of exercise behavior of the grantees. The risk-free rate for periods within the contractual life of the options is based on the market yield of U.S. Treasury Bonds in effect at the time of grant. Prior to th IPO, the estimated fair value of the ordinary shares, at the option grant dates, were determined by the assistance of an independent third-party valuation firm. Subsequent to the IPO, fair value of the common shares is the price of the Company’s publicly traded shares. The Company’s management is ultimately responsible for the determination of the estimated fair value of its ordinary shares.

The Company recognizes stock-based compensation expense using the accelerated recognition method over the requisite service period, which is generally subject to graded vesting.

11Share-based compensation (continued)

The following table presents assumptions used to estimate the fair values of share options granted for the year ended December 31, 2017 and 2018:

	2016		2017		2018
Risk-free interest rate	1.83% - 1.84%		2.27% - 2.41%		2.27% - 2.93%
Dividend yield	0%		0%		0%
Expected volatility	47.33% - 47.60%		46.33% - 47.15%		45.30% - 46.10%
Weighted average expected volatility	47.44%		46.66%		45.98%
Expected exercise multiple		2.5		2.5		2.5

(i)	Risk-free interest rate – The risk-free interest rate for periods within the contractual life of the options is based on the US Treasury yield curve in effect at the time of the grant for a term consistent with the contractual term of the awards.

(ii)	Dividend yield – The dividend yield is estimated based on the Company’s expected dividend policy over the expected term of the options.

(iii)

Expected volatility – Expected volatility is estimated based on the historical volatility of common shares of several comparable publicly-traded companies in the same industry.

(iv)	Expected exercise multiple – expected exercise multiple is estimated based on changes in expected intrinsic value of the option and the likelihood of early exercise by employees.

Restricted share units

Starting from September 4, 2018, the Company granted restricted Class A common shares of the Company (“Restricted Shares”).

A summary of the restricted share units for the year ended December 31, 2018 was stated below:

Restricted Share Units Granted to Employees and Directors	Number of Share Units		Weighted-Average Exercise Price		Weighted- Average grant-date Fair Value per Option		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
			RMB		RMB				RMB
Outstanding, December 31, 2017		—		—		—		—		—
Granted		12,550		—		54.69		9.68		907
Forfeited		—		—		—		—		—
Expired		—		—		—		—		—
Exercised		—		—		—		—		—
Cancelled		—		—		—		—		—
Outstanding, December 31, 2018		12,550		—		54.69		9.68		907
Vested and expected to vest at December 31, 2018		12,550		—		54.69		9.68		907
Exercisable at December 31, 2018		—		—		—		—		—

The weighted average grant-date fair value per share of restricted share units granted for the year ended December 31, 2018 was RMB54.69 (US$7.95).

As of December 31, 2018, there was RMB447 (US$68) of unrecognized share-based compensation cost related to restricted shares, which the Company expects to recognize over an estimated weighted-average period of one year.

11Share-based compensation (continued)

Total compensation costs recognized for the year ended December 31, 2017 and 2018 were as follows:

	Year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Research and development		664		1,408		9,448		1,374
Sales and marketing		189		944		3,347		487
General and administrative		1,850		5,923		11,766		1,711
Total		2,703		8,275		24,561		3,572

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

12	Income taxes

Cayman Islands

Under the current tax laws of Cayman Islands, the Company and its subsidiaries are not subject to tax on income or capital gains. Besides, upon payment of dividends by the Company to its shareholders, no Cayman Islands withholding tax will be imposed.

British Virgin Islands

Under the current laws of the British Virgin Islands (“BVI”), the Company’s BVI incorporated subsidiary are not subject to tax on income or capital gains arising in BVI. In addition, upon payments of dividends by this entity to its shareholders, no BVI withholding tax will be imposed.

Hong Kong

Under the Hong Kong tax laws, the subsidiary in Hong Kong are subject to the Hong Kong profits tax rate at 16.5% and it may be exempted from income tax on its foreign-derived income and there are no withholding taxes in Hong Kong on remittance of dividends.

China

Effective from January 1, 2008, the PRC’s statutory, Enterprise Income Tax (“EIT”) rate is 25%. In accordance with the implementation rules of EIT Law, a qualified “High and New Technology Enterprise” (“HNTE”) is eligible for a preferential tax rate of 15%. The HNTE certificate is effective for a period of three years. An entity must file required supporting documents with the tax authority and ensure fulfillment of the relevant HNTE criteria before using the preferential rate. An entity could re-apply for the HNTE certificate when the prior certificate expires.

The VIE in the PRC was recognized as a qualified HNTE under the EIT Law by relevant government authorities in 2016. It was entitled to the preferential rate of 15% for 2017 and 2018.

The WFOE in the PRC is subject to the 25% EIT rate.

The Company’s profit/(loss) before income taxes consists of:

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Cayman Islands		(3,214	)		(10,584	)		6,622			964
British Virgin Islands		(4	)		(2	)		(25	)		(4	)
Hong Kong		563			(34	)		208			30
China		(54,817	)		(83,651	)		(72,972	)		(10,613	)
Total loss before income taxes		(57,472	)		(94,271	)		(66,167	)		(9,623	)

12	Income taxes (continued)

Composition of income tax expense

The current and deferred portions of income tax expense included in the consolidated statements of comprehensive loss are as follows:

	As of December 31,
	2016			2017		2018
	RMB			RMB		RMB			US$
Current income tax expense		—			—		(35	)		(5	)
Deferred tax (expense)/benefit		(3,910	)		3,980		5			1
Total income tax (expense)/benefit		(3,910	)		3,980		(30	)		(4	)

Reconciliation between expenses of income taxes

Reconciliation between the expense of income taxes computed by applying the statutory tax rate to loss before income taxes and the actual provision for income taxes is as follows:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Loss before income tax		(94,271	)		(66,167	)		(9,623	)
Income tax expense computed at PRC statutory rate (25%)		(23,569	)		(16,542	)		(2,408	)
International tax rate differential		2,650			(1,668	)		(243	)
Preferential tax rate		4,004			6,397			930
Deferred tax items tax rate differential		(4,951	)		(6,390	)		(929	)
Research and development super-deduction		(7,787	)		(21,559	)		(3,134	)
Non-deductible expenses		1,482			5,701			829
Outside basis differences		(7,475	)		—			—
Deferred tax expense		—			4,073			592
Changes in valuation allowance		31,666			30,018			4,367
Income tax expense/(benefit)		(3,980	)		30			4

12	Income taxes (continued)

Deferred tax assets and liabilities

Deferred taxes were measured using the enacted tax rates for the periods in which the temporary differences are expected to be reversed. The tax effects of temporary differences that give rise to the deferred tax balances as of December 31, 2017 and 2018 are as follows:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Deferred tax assets, net
Provision for doubtful debts		866			2,463			358
Accrued expense		231			3,737			543
Net operating loss carry forward		54,079			78,985			11,489
Government grant related to assets		69			54			8
Fixed assets depreciation		—			14			2
Estimated liabilities		—			10			2
Valuation allowance		(55,245	)		(85,263	)		(12,401	)
Total deferred tax assets, net		—			—			—
Deferred tax liabilities
Fixed assets depreciation		5			—			—
Total deferred tax liabilities		5			—			—

The Company operates through its WFOE and VIE and evaluates the potential realization of deferred tax assets on an entity basis. The Company recorded valuation allowance against deferred tax assets of those entities that were in a three-year cumulative financial loss and are not forecasting profits in the near future as of December 31, 2017 and 2018. In making such determination, the Company also evaluated a variety of factors including the Company’s operating history, accumulated deficit, existence of taxable temporary differences and reversal periods.

The Company had deferred tax assets related to net operating loss carry forwards of RMB54,079 and RMB78,985 (US$11,489) from its WFOE and the VIE in China, which can be carried forward to offset taxable income. The net operating loss of WOFE and VIE will expire in years 2019 to 2023 and 2019 to 2028 if not utilized, respectively.

The Company did not record any dividend withholding tax, as there were no undistributed earnings arising from the WFOE noted as of December 31, 2017 and 2018.

As of December 31, 2017 and 2018, the Company concluded that there was no significant tax uncertainties in its consolidated financial results. The Company did not record any interest and penalties related to an uncertain tax position for each of the year ended December 31, 2017 and 2018. The Company does not expect the amount of unrecognized tax benefits would increase significantly in the next 12 months. In general, the PRC tax authorities have up to five years to conduct examinations of the tax filings of the Company’s PRC subsidiary and the VIE. Accordingly, the PRC tax filings from 2013 through 2018 remain open to examination by the respective tax authorities. The Company may also be subject to the examinations of the tax filings in other jurisdictions, which are not material to the consolidated financial statements.

Convertible Notes

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Convertible Notes

13	Convertible notes

On April 17, 2018, the Company issued zero coupon convertible notes (the “Convertible Notes”) due 2021 in an aggregate principal amount of US$35,000 to one existing and one new investor. The Convertible Notes will mature on their third anniversary date. Holders of the convertible notes may, at their option during a period starting from the issue date until seven days prior to the maturity of the notes, subject to certain exceptions, convert the notes into common shares of the Company at the then applicable conversion price, which is initially US$11.76 per share, subject to certain anti-dilution and other adjustments (the “Conversion Option”). On the commitment date, the conversion option did not qualify for derivative accounting as the underlying common shares which the Convertible Note could be converted into were not publicly traded nor could they be readily convertible into cash in accordance with ASC 815-15 and ASC 815-40. Upon the initial public offering, whilst the net settlement criteria is subsequently met, the Conversion Option continued not to qualify for derivative accounting as it meets the scope exception provided for under ASC 815-10-15-74(a).

If no qualified IPO were to occur within two years of the issue date, the outstanding obligation at their principal amount with an amount representing a total internal rate of return of 8% per annum, under the Convertible Notes would be immediately due and payable (“Contingent Redemption Option”). If the event of default as defined in the Convertible Notes were to occur, a simple interest of 15% will accrue on the principal. If the Company fails to deliver and register title to any shares following conversion of any Convertible Note, an interest represents a total internal rate of return of 15% per annum will accrue on the principal (both “Contingent Interest Feature”).

The debt issuance costs of the Convertible Notes is US$1,275. The Company evaluated and determined if there were any embedded derivatives requiring bifurcation and to determine if there were any beneficial conversion features (“BCF”).

The Company also evaluated the Contingent Redemption Option and Contingent Interest Feature contained in the Convertible Notes in accordance with ASC 815. Both features qualify for derivative accounting as they are not clearly and closely related to the debt host and will be accounted for as a single compound derivative. At issuance date, the Company recognized a derivative liability of US$3,224, which was subsequently accounted for at fair value with a change in fair value of US$3,224 recognized in current earnings for the year ended December 31, 2018 due to a qualified IPO.

Furthermore, as the most favorable conversion price used to measure the BCF for the Convertible Note was the issuance price of US$11.76, no BCF was recognized for the Convertible Note as the fair value per ordinary share at the commitment date was US$9.87, which was less than the most favorable conversion price.

Both principal amount subsequent to the bifurcation of its compound derivative and the issuance costs are amortized as interest expense using the effective interest rate method through the maturity dates of the convertible notes. The effective interest rate was 4.69%.

The principal amount, debt issuance costs and derivative liability as of December 31, 2018 was as follows:

	As of April 17, 2018			Charge to profit and loss			Foreign currency translation adjustment		As of December 31, 2018
	RMB			RMB			RMB		RMB			US$
Principal amount		219,699			—			20,513		240,212			34,937
Issuance costs		(8,436	)		—			—		(8,436	)		(1,227	)
Contingent redemption feature		(19,805	)		—			4,208		(15,597	)		(2,268	)
Convertible notes		191,458			—			24,721		216,179			31,442
Derivative liability		20,237			(21,302	)		1,065		—			—
Total		211,695			(21,302	)		25,786		216,179			31,442

As of December 31, 2018, aggregate future principal payments for the Convertible Notes were as follows:

	RMB		US$
1 year (Including 1 year)		—		—
1 year to 2 years (Including 2 years)		—		—
2 years to 3 years (Including 3 years)		240,212		35,000
Total		240,212		35,000

Commitment and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

14Commitments and contingencies

Operating lease commitments

The Company leases office premises and printers in the PRC under non-cancellable operating leases expiring on different dates. Payments under operating leases are expensed on a straight-line basis over the periods of the respective leases.

Total operating lease expenses were RMB3,113, RMB6,081 and RMB12,120 (US$1,763) for the year ended December 31, 2016, 2017 and 2018, respectively.

As of December 31, 2018, future minimum payments under non-cancellable operating leases were as follows:

	RMB		US$
2019		13,387		1,947
2020		10,573		1,538
2021		4,613		671
2022 and thereafter		4,478		651
Total		33,051		4,807

The Company’s operating lease commitments have no renewal options, rent escalation clauses and restrictions or contingent rents.

Capital commitments

As of December 31, 2018, future minimum payment under non-cancellable purchase commitment for bandwidth is RMB1,744 (US$254), which is scheduled to be paid within one year; for consulting service is RMB7,008 (US$1,019) and RMB271 (US$39), which is scheduled to be paid within one and two years, respectively.

Share Capital

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Share capital

15	Share capital

On June 27, 2018, the Company’s shareholders adopted a resolution to approve the Post-Offering Memorandum and Articles of Association, The Post-Offering Memorandum and Articles of Association provide that, the Company’s authorized share capital will be changed into US$500 divided into 5,000,000,000 shares.

As of December 31, 2017, there were 42,666,670 common shares and 27,867,937 preferred shares.

On April 11, 2018, the Company redeemed the 1,738,720 Series C preferred shares held by T.C.L. Industries Holdings (H.K.) Ltd. for an aggregate price of US$9,049,000.

On July 26, 2018, the Company completed its IPO on the NASDAQ. The Company offered 9,060,000 ADSs representing 6,040,000 Class A common shares. Upon completion of the IPO, all outstanding 27,867,937 Preferred Shares were converted on a one-for-one basis into 27,867,937 Class A common shares, all 42,666,670 outstanding common shares were converted on a one-for-one basis into 25,666,481 Class A common shares and 17,000,189 Class B common shares, respectively. Holders of Class A common shares and Class B common shares will have the same rights except for voting and conversion rights. In respect of all matters subject to a shareholder vote, each Class A common share is entitled to one vote, and each Class B common share is entitled to ten votes, voting together as one class. Each Class B common share is convertible into one Class A common share at any time by the holder thereof. Class A common shares are not convertible into Class B common shares under any circumstances. Upon any transfer of Class B common shares by a holder thereof to any person or entity that is not an affiliate of such holder, such Class B common shares shall be automatically and immediately converted into the same number of Class A common shares.

Additionally, on August 30, 2018, the underwriters exercised their over-allotment option and issued more 19,708 Class A common shares. And as of December 31, 2018, the Company had repurchased under the Share Repurchase Program an aggregate of 69,455 ADSs, representing 46,303 Class A common shares (notes 12).

15	Share capital (continued)

On November 20, 2018, the Board of Directors of the Company authorized the Repurchase Plan, pursuant to which the Company was authorized to repurchase its own issued and outstanding American depositary shares (“ADSs”) up to an aggregate value of US$10 million from the open market.

As of December 31, 2018, the Company had repurchased under the Repurchase Plan an aggregate of 69,455 ADSs, representing 46,303 Class A common shares. The Company has no plan for cancellation of these repurchased shares. These shares were recorded at their purchase cost on the consolidated balance sheets.

As at December 31, 2018 there were 59,547,823 and 17,000,189 Class A and Class B ordinary shares outstanding respectively.

Basic and diluted loss per share is calculated as follows:

	For the year ended December 31, 2016			For the year ended December 31, 2017			For the year ended December 31, 2018
	Common shares			Common shares			Class A						Class B
	RMB			RMB			RMB			US$			RMB			US$
Numerator:
Net loss attributable to Class A and Class B common shareholders		(61,382	)		(90,291	)		(46,606	)		(6,779	)		(19,591	)		(2,848	)
Deduct: Accretion of redeemable convertible preferred shares		(12,427	)		(26,391	)		(16,963	)		(2,467	)		(7,131	)		(1,037	)
Net Loss attributable to common shareholders		(73,809	)		(116,682	)		(63,569	)		(9,246	)		(26,722	)		(3,885	)
Denominator:
Weighted average number of shares used in calculating basic and diluted loss per share		42,666,670			42,666,670			40,441,999			40,441,999			17,000,189			17,000,189
Basic and diluted loss per share		(1.73	)		(2.73	)		(1.57	)		(0.23	)		(1.57	)		(0.23	)

For the years ended December 31, 2016 and 2017, the computation of basic loss per share using the two-class method is not applicable as the Company only had one class of common shares and the Preferred Shares do not have contractual rights and obligations to share in the losses of the Company. For the year ended December 31, 2018, the two-class method is applicable because the Company has Class A and Class B ordinary shares outstanding, and both classes have contractual rights with regards to dividends and distributions upon liquidation of the Company. The effect of all outstanding Preferred Shares, share options, restricted share units and convertible notes were excluded from the computation of diluted loss per share for the years ended December 31, 2016, 2017 and 2018 as their effects would be anti-dilutive.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

Related Party Transactions

16	Related party transactions

The table below sets forth the major related parties and their relationships with the Company:

Name of related parties		Relationship
KK Mobile Limited		Principal owner of the Company, controlled by Weidong Luo
Stable View Limited		Shareholder of the Company, controlled by Jiawen Fang, who is a director of the Company.
Focus Axis Limited		Shareholder of the Company, controlled by Xiaodao Wang, who is a director of the Company.
Weidong Luo		Founder, Chief Executive Officer
Fei Chen		Founder, President
Shenzhen Weixunyitong Information Technology Co., Ltd.		Company that is significantly influenced by Weidong Luo
Guangzhou Tianlang Network Technology Co., Ltd.		Company that is significantly influenced by Weidong Luo

Details of related party balances and transactions as of December 31, 2016, 2017 and 2018 are as follows:

16.1 Amounts due from related parties

	As of December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Focus Axis Limited		2		17		—		—
KK Mobile Limited		26		40		—		—
Stable View Limited		2		17		—		—
Shenzhen Weixunyitong Information Technology Co., Ltd.		65		886		1,543		224
Guangzhou Tianlang Network Technology Co., Ltd.		—		300		1,305		190
President		—		—		1,716		250
Total amounts due from related parties		95		1,260		4,564		664

16.2 Amounts due to related parties

	As of December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Weidong Luo		5,649		5,649	—		—
Shenzhen Weixunyitong Information Technology Co., Ltd.		504		461		8,864		1,289
Guangzhou Tianlang Network Technology Co., Ltd.		200	—		—		—
Total amounts due to related parties		6,353		6,110		8,864		1,289

16	Related party transactions (continued)

16.3 Transactions with related parties

	For the year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Services provided to:
Shenzhen Weixunyitong Information Technology Co., Ltd.		344		2,752		1,002		142
Guangzhou Tianlang Network Technology Co., Ltd.	—			755		1,542		224
Total		344		3,507		2,544		366
Services received from:
Shenzhen Weixunyitong Information Technology Co., Ltd.		360		672		20,909		3,041
Office premises leased from:
Shenzhen Weixunyitong Information Technology Co., Ltd.		1,193		1,557		475		69
Marketing expense incurred:
Guangzhou Tianlang Network Technology Co., Ltd.		943	—		—		—
Total		2,496		2,229		21,384		3,110

Revenues

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Revenues

Revenues consist of the following:

	Year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Developer services		23,196		38,795		60,106		8,742
Data solutions
Targeted Marketing		43,149		221,153		572,796		83,310
Other vertical data solutions		3,977		24,761		81,239		11,816
Total data solutions		47,126		245,914		654,035		95,126
Total revenues		70,322		284,709		714,141		103,868

Fair value measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair value measurements

18Fair value measurements

Financial instrument includes convertible notes and their bifurcated embedded redemption feature derivative. The carrying value of the convertible notes is RMB nil and RMB216,179 as of December 31, 2017 and 2018, respectively. The fair value measurement of the convertible notes falls into level 3 of the fair value hierarchy.

The Company measures bifurcated embedded redemption feature derivative of convertible notes at fair value on a recurring basis, which is classified within Level 3 as the fair value is measured based on risk-free interest rate, volatility, mature date, conversion price, and other factors.

The Company carries the convertible notes at face value less unamortized debt discount and issuance costs on its consolidated balance sheets, and presents the fair value for required disclosure purposes only. The Company classified the fair value of convertible notes as Level 3 within the fair value hierarchy due to the lack of observable market data and activity. For further information on the convertible notes see Note 13.

The changes in fair value of the redemption feature derivative liability during fiscal years 2017 and 2018 are shown in the following table.

	Fair value measurements
	Quoted prices in active market for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)			Total
As of December 31, 2017 in RMB		—		—		—			—
Derivative liability						20,237			20,237
Foreign currency translation adjustment						1,065			1,065
Charge to profit and loss		—		—		(21,302	)		21,302
As of December 31, 2018 in RMB		—		—		—			—
As of December 31, 2018 in USD		—		—		—			—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Restricted Net Assets

12 Months Ended

Dec. 31, 2018

Restricted Net Assets [Abstract]

Restricted Net Assets

19	Restricted net assets

The Company’s ability to pay dividends is primarily dependent on the Company receiving distributions of funds from its subsidiaries. Relevant PRC statutory laws and regulations permit payments of dividends by the VIE incorporated in PRC only out of their retained earnings, if any, as determined in accordance with PRC accounting standards and regulations. The consolidated results of operations reflected in the consolidated financial statements prepared in accordance with U.S. GAAP differ from those reflected in the statutory financial statements of the Company’s subsidiaries.

Under PRC law, the Company’s subsidiary and VIE located in the PRC (collectively referred as the “PRC entities”) are required to provide for certain statutory reserves, namely a general reserve, an enterprise expansion fund and a staff welfare and bonus fund. The PRC entities are required to allocate at least 10% of their after tax profits on an individual company basis as determined under PRC accounting standards to the statutory reserve and has the right to discontinue allocations to the statutory reserve if such reserve has reached 50% of registered capital on an individual company basis. In addition, the registered capital of the PRC entities is also restricted.

Appropriations to the enterprise expansion fund and staff welfare and bonus fund are at the discretion of the Board of Directors of the subsidiary. The PRC entities are also subject to similar statutory reserve requirements. These reserves can only be used for specific purposes and are not transferable to the Company in the form of loans, advances or cash dividends.

Amounts of net assets restricted include paid-in capital and statutory reserve of the Company’s PRC subsidiary and the net assets of the VIE in which the Company has no legal ownership, totaling RMB280,922 (US$44,786) and RMB787,223 (US$114,497) as of December 31, 2017 and 2018, respectively.

Condensed Financial Information of the Parent Company

12 Months Ended

Dec. 31, 2018

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Condensed Financial Information of the Parent Company

21	Condensed financial information of the parent company

Basis of presentation

For the presentation of the parent company only condensed financial information, the Company records its investments in subsidiaries and VIE under the equity method of accounting as prescribed in ASC 323, Investments—Equity Method and Joint Ventures. Such investments are presented on the condensed balance sheets as "Long term investment" and the subsidiaries' and VIE's losses as "Share of losses of subsidiaries and VIE" on the condensed statements of comprehensive loss.

The subsidiaries did not pay any dividends to the Company for the periods presented.

The Company does not have significant commitments or long-term obligations as of the period end other than those presented.

The parent company only financial statements should be read in conjunction with the Company's consolidated financial statements.

21	Condensed financial information of the parent company (continued)

Condensed Balance Sheets

	As of December 31,
	2017			2018
	RMB			RMB			US$
ASSETS:
Current assets:
Cash and cash equivalents		118,429			238,236			34,650
Due from the entities within the Group		6,603			7,030			1,022
Prepayments		—			2,439			355
Interest receivables		—			89			13
Amounts due from related parties		28			—			—
Other receivables		—			1,717			251
Total current assets		125,060			249,511			36,291
Non-current assets:
Long-term investments		126,616			590,752			85,921
Intangible assets		—			93			14
Total non-current assets		126,616			590,845			85,935
Total assets		251,676			840,356			122,226
LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS DEFICIT
Current liabilities:
Accrued liabilities and other current liabilities		3,072			11,542			1,679
Due to the entities within the Group		702			710			103
Amounts due to related parties		5,649			—			—
Total current liabilities		9,423			12,252			1,782
Non-current liabilities:
Deferred revenue - non-current		—			10,265			1,493
Convertible notes		—			216,179			31,442
Total non-current liabilities		—			226,444			32,935
Total liabilities		9,423			238,696			34,717
Mezzanine equity
Series A contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 11,111,120 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		26,979			—			—
Series B contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 7,936,510 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		52,723			—			—
Series C contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 4,999,540 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		168,317			—			—
Series D contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 5,559,487 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		218,618			—			—
Total mezzanine equity		466,637			—			—
Shareholders’ deficit
Common shares (par value of US$0.0001 and nil per share as of December 31, 2017 and 2018; 470,393,343 and 50,000,000 shares authorized as of December 31, 2017 and 2018, 42,666,670 and nil shares issued and outstanding as of December 31, 2017 and 2018, respectively)		26			—			—
Class A common shares (par value of nil and US$0.0001 per share as of December 31, 2017 and 2018; nil and 4,920,000,000 shares authorized as of December 31, 2017 and 2018, nil and 59,547,823 shares issued and outstanding as of December 31, 2017 and 2018, respectively)		—			37			5
Class B common shares (par value of nil and US$0.0001 per share as of December 31, 2017 and 2018; nil and 30,000,000 shares authorized as of December 31, 2017 and 2018, nil and 17,000,189 shares issued and outstanding as of December 31, 2017 and 2018)		—			11			2
Treasury shares (nil and 46,303 class A common shares as of December 31, 2017 and 2018, respectively)		—			(3,165	)		(460	)
Additional paid-in capital		13,689			944,500			137,372
Accumulated deficit		(234,810	)		(348,123	)		(50,632	)
Accumulated other comprehensive loss		(3,289	)		8,400			1,221
Total shareholders’ deficit		(224,384	)		601,660			87,508
Total liabilities, mezzanine equity and shareholders’ deficit		251,676			840,356			122,226

21	Condensed financial information of the parent company (continued)

Condensed Statements of Comprehensive Loss

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Revenues		—			—			—			—
Cost of Revenues		—			—			—			—
Gross profit		—			—			—			—
Operating expenses
Research and development		—			—			—			—
Sales and marketing		—			—			—			—
General and administrative		(2,302	)		(10,076	)		(11,941	)		(1,737	)
Share of losses of subsidiaries and the VIE		(58,167	)		(79,916	)		(72,750	)		(10,581	)
Total operating expenses		(60,469	)		(89,992	)		(84,691	)		(12,318	)
Loss from operations		(60,469	)		(89,992	)		(84,691	)		(12,318	)
Foreign exchange loss, net		(961	)		(339	)		(186	)		(27	)
Interest income		48			18			3,013			438
Interest expense		—			—			(6,599	)		(960	)
Other income		—			22			22,266			3,238
Loss before income taxes		(61,382	)		(90,291	)		(66,197	)		(9,629	)
Income tax expenses		—			—			—			—
Net Loss		(61,382	)		(90,291	)		(66,197	)		(9,629	)
Accretion of contingently redeemable convertible preferred shares		(12,427	)		(26,391	)		44,451			6,465
Net loss attributable to common share holders		(73,809	)		(116,682	)		(21,746	)		(3,164	)
Other comprehensive income (loss)
Foreign currency translation adjustments		1,896			(7,563	)		29,510			4,292
Total other comprehensive income (loss), net of tax		1,896			(7,563	)		29,510			4,292
Comprehensive loss		(59,486	)		(97,854	)		(36,687	)		(5,337	)

Condensed Statements of Cash Flows

	For the year ended December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Net cash used in operating activities		(2,311	)		(744	)		16,052			2,335
Net cash used in investing activities		(77,193	)		(157,412	)		(535,995	)		(77,957	)
Net cash from financing activities		134,348			217,446			614,884			89,431
Effect of exchange rate changes		2,649			(7,695	)		24,866			3,617
Net increase in cash and cash equivalents		57,493			51,595			119,807			17,426
Cash and cash equivalents and restricted cash at the beginning of year		9,341			66,834			118,429			17,224
Cash and cash equivalents and restricted cash at the end of year		66,834			118,429			238,236			34,650

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of presentation

The consolidated financial statements of the Company have been prepared in accordance with the generally accepted accounting principles of the United States (“U.S. GAAP”).

Principles of Consolidation

Use of estimates

Convenience translation

2	Summary of Significant Accounting Policies (continued)

Convenience translation

Foreign currency translation

Transactions in currencies other than the functional currency are remeasured and recorded in the functional currency at the exchange rate prevailing on the transaction date.

Cash and cash equivalents

Restricted cash

Restricted cash represents cash granted by the government and designated only for the purchase of property and equipment for certain approved projects.

Accounts receivable and allowance for doubtful accounts

Property and equipment, net


Computer equipment and servers		3 – 5 years
Office furniture and equipment		3 – 5 years
Leasehold improvements		over the shorter of lease terms or estimated useful lives of the assets

Intangible assets

2	Summary of Significant Accounting Policies (continued)

Intangible assets

Computer software and systems

1 – 3 years

Impairment of long-lived assets other than goodwill

Long-term Investments

Long-term investments

Deferred revenue and customer deposits

Convertible notes

Value added taxes (“VAT”)

2	Summary of Significant Accounting Policies (continued)

Value added taxes (“VAT”)

Share split

Treasury shares

Revenue recognition

2	Summary of Significant Accounting Policies (continued)

Revenue recognition

Data solutions

Developer services

Costs of revenues

Research and development

Advertising expense

2	Summary of Significant Accounting Policies (continued)

Other income

Government grants

Operating leases

Employee defined contribution plan

Income taxes

2	Summary of Significant Accounting Policies (continued)

Income taxes (continued)

The Company did not recognize any income tax due to uncertain tax position or incur any interest and penalties related to potential underpaid income tax expenses during the years presented.

Share-based compensation

Fair value measurements

Level 1-Quoted prices in active markets for identical assets or liabilities.

Level 3-Inputs that are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability.

Comprehensive loss

Loss per share

Concentration of risks

Concentration of credit risk

Financial assets that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash, short-term investments and accounts receivable.

Concentration of suppliers

Approximately 81.3% and 50.9% of advertising costs were paid to three suppliers for the year ended December 31, 2017 and 2018, respectively.

Business and economic risk

Currency convertibility risk

Foreign currency exchange rate risk

Segment information

2	Summary of Significant Accounting Policies (continued)

Segment information

As the Company generates substantially most of its revenues in the PRC, no geographical segments is presented.

Recently issued accounting pronouncements

Step 1: Identify the contract(s) with a customer.

Step 2: Identify the performance obligations in the contract.

Step 3: Determine the transaction price.

Step 4: Allocate the transaction price to the performance obligations in the contract.

Step 5: Recognize revenue when (or as) the entity satisfies a performance obligation.

2	Summary of Significant Accounting Policies (continued)

Recently issued accounting pronouncements (continued)

2	Summary of Significant Accounting Policies (continued)

Recently issued accounting pronouncements (continued)

Organization and Principal Activities (Tables)

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Assets and Liabilities of VIE

The following table set forth the assets and liabilities of the VIE included in the Company’s consolidated balance sheets:

	As of December 31,
	2017		2018
	RMB		RMB		US$
ASSETS:
Current assets:
Cash and cash equivalents		49,853		31,763		4,620
Restricted cash		115		115		17
Accounts receivable		49,561		141,705		20,609
Prepayments and other current assets		29,637		64,532		9,386
Amounts due from the Company and its subsidiaries		3,806		3,965		577
Amounts due from related parities		1,186		2,848		414
Total current assets		134,158		244,928		35,623
Non-current assets:
Long-term investments		10,000		71,512		10,401
Other receivables-non current		1,354		2,529		368
Property and equipment, net		24,258		46,271		6,730
Intangible assets, net		283		1,406		204
Long-term prepayment		—		11,000		1,600
Total non-current assets		35,895		132,718		19,303
Total assets		170,053		377,646		54,926
LIABILITIES:
Current liabilities:
Accounts payable		8,340		18,683		2,717
Deferred revenue and customer deposits		48,085		55,625		8,091
Accrued liabilities and other current liabilities		31,631		59,556		8,662
Amounts due to the Company and its subsidiaries		39,861		15,534		2,259
Amounts due to related parties		459		8,864		1,289
Total current liabilities		128,376		158,262		23,018
Non-current liabilities:
Amounts due to the Company and its subsidiaries		60,000		240,000		34,907
Other non-current liabilities		216		140		20
Deferred tax liabilities		5		—		—
Deferred revenue and customer deposits		330		—		—
Total non-current liabilities		60,551		240,140		34,927
Total liabilities		188,927		398,402		57,945

Summary of Results of Operations and Cash Flows of VIE

1	Organization and principal activities (continued)

The table sets forth the results of operations and cash flows of the VIE included in the company’s consolidated statements of comprehensive loss and cash flows.

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Revenues		70,148			284,348			709,594			103,206
Cost of revenues		(47,559	)		(206,789	)		(499,589	)		(72,662	)
Net income/(loss)		18,681			(40,003	)		(16,785	)		(2,441	)
Net cash used in operating activities		7,590			(51,016	)		(68,316	)		(9,936	)
Net cash used in investing activities		—			(10,000	)		(104,675	)		(15,224	)
Net cash provided by financing activities		1,000			—			154,901			22,529

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Property and Equipment

The estimated useful lives of property and equipment are as follows:


Computer equipment and servers		3 – 5 years
Office furniture and equipment		3 – 5 years
Leasehold improvements		over the shorter of lease terms or estimated useful lives of the assets

Schedule of Finite Lived Intangible Assets Estimated Economic Lives

All intangible assets with finite lives are amortized using the straight-line method over the estimated economic lives, which are as follows:

Computer software and systems

1 – 3 years

Intangible assets consist of the following:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Computer software and systems		319			1,874			273
Less: Accumulated amortization		(36	)		(343	)		(50	)
Total intangible assets, net		283			1,531			223

Accounts Receivable, Net (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Schedule of Accounts Receivable

	As of December 31,
	2017			2018
	RMB			RMB			US$
Accounts receivable		53,056			151,219			21,994
Less: allowance for doubtful accounts		(3,462	)		(9,308	)		(1,354	)
Total accounts receivable, net		49,594			141,911			20,640

Schedule of Movement in Allowance for Doubtful Accounts

The following table presents the movement in the allowance for doubtful accounts:

	As of December 31,
	2017		2018
	RMB		RMB			US$
Balance at beginning of year		1,035		3,462			504
Provisions		2,427		6,389			929
Write-offs		—		(543	)		(79	)
Balance at end of year		3,462		9,308			1,354

Prepayment and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2018

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

'Schedule of Prepayment and Other Current Assets

Prepayment and other current assets consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Prepaid media cost		19,610		54,937		7,990
Prepaid service fee		1,762		6,804		989
Others		12,856		18,837		2,740
Total prepayment and other current assets		34,228		80,578		11,719

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consist of the following:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Office furniture and equipment		2,647			4,920			716
Computer equipment and servers		63,326			111,274			16,184
Leasehold improvements		789			7,256			1,055
Less: Accumulated depreciation		(13,739	)		(30,576	)		(4,447	)
Total property and equipment, net		53,023			92,874			13,508

Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Schedule of Finite Lived Intangible Assets Estimated Economic Lives

All intangible assets with finite lives are amortized using the straight-line method over the estimated economic lives, which are as follows:

Computer software and systems

1 – 3 years

Intangible assets consist of the following:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Computer software and systems		319			1,874			273
Less: Accumulated amortization		(36	)		(343	)		(50	)
Total intangible assets, net		283			1,531			223

Schedule of Estimated Amortization Expense Related to the Existing Intangible Assets

Estimated amortization expense relating to the existing intangible assets with finite lives for each of the next five years is as follows:

	RMB		US$
For the year ending December 31, 2019		749		109
2020		464		67
2021		318		47
2022		—		—
2023		—		—

Long-Term Investments (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Schedule of Long-Term Investments

As of December 31, 2017 and 2018, long-term investments consisted of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Cost method investments		10,980		79,696		11,591
Less: Impairment loss		—		—		—
Total		10,980		79,696		11,591

Deferred Revenue and Customer Deposits (Tables)

12 Months Ended

Dec. 31, 2018

Revenue Recognition And Deferred Revenue [Abstract]

Deferred Revenue, by Arrangement

Deferred revenue and customer deposits consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Deferred revenue		28,921		33,067		4,809
Customer deposits		20,636		26,416		3,842
Total deferred revenue and customer deposits — current		49,557		59,483		8,651
Deferred revenue — non-current		330		10,265		1,493

Schedule of Roll Forward of Customer Deposits

8	Deferred revenue and customer deposits (continued)

Roll-forward of customers deposits:

	Year ended December 31,
	2017			2018
	RMB			RMB			US$
Balance at beginning of year		6,064			20,636			3,001
Cash received from customers during the year		129,555			407,630			59,287
Revenue recognized during the year		(112,770	)		(397,488	)		(57,812	)
Refunds paid during the year		(2,213	)		(4,362	)		(634	)
Balance at end of year		20,636			26,416			3,842

Accrued Liabilities and Other Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities and Other Current Liabilities

Accrued liabilities and other current liabilities consist of the following:

	As of December 31,
	2017		2018
	RMB		RMB		US$
Accrued payroll and welfare payables		38,704		51,607		7,506
Other taxes and surcharge		2,676		11,277		1,640
Service fees		560		11,130		1,619
Acquisition of fixed assets		9,731		104		15
Others		968		2,548		371
Total accrued liabilities and other current liabilities		52,639		76,666		11,151

Contingently Redeemable Convertible Preferred Shares (Tables)

12 Months Ended

Dec. 31, 2018

Temporary Equity [Abstract]

Schedule of Movement in Carrying Value of Convertible Preferred Shares

The movement in the carrying value of the convertible preferred shares is as follows:

Mezzanine equity	Series A			Series B			Series C			Series D			Total
	RMB			RMB			RMB			RMB			RMB
Balance as of December 31, 2016		26,804			52,044			141,691			—			220,539
Issuance of Series C preferred shares		—			—			20,571			—			20,571
Issuance of Series D preferred shares		—			—			—			206,359			206,359
Issuance cost of Series D preferred shares		—			—			—			(7,223	)		(7,223	)
Accretion of Preferred Shares		175			679			6,055			19,482			26,391
Balance as of December 31, 2017		26,979			52,723			168,317			218,618			466,637
Accretion of Preferred Shares		1,463			4,137			7,441			11,053			24,094
Redemption of Preferred Shares		—			—			(57,234	)		—			(57,234	)
Conversion of Preferred Shares		(28,442	)		(56,860	)		(118,524	)		(229,671	)		(433,497	)
Balance as of December 31, 2018		—			—			—			—			—
Balance as of December 31, 2018 (US$)		—			—			—			—			—

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Share Option Activity

The following table summarizes the share option activity for the year ended December 31, 2018:

Options Granted to Employees and Directors	Number of Options		Weighted- Average Exercise Price		Weighted- Average grant-date Fair Value per Option		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
			RMB		RMB				RMB
Outstanding, December 31, 2016		5,472,031		2.32		2.13		7.89		34,255
Granted		894,115		16.29		10.34		—		—
Forfeited		—		—		—		—		—
Expired		—		—		—		—		—
Exercised		—		—		—		—		—
Cancelled		—		—		—		—		—
Outstanding, December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Vested and expected to vest at December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Outstanding, December 31, 2017		6,366,146		4.33		3.31		7.21		95,559
Granted		1,736,390		26.68		45.72		—		—
Forfeited		55,520		26.55		24.69		—		—
Expired		—		—		—		—		—
Exercised		—	—		—		—		—
Cancelled		14,558		6.56		1.87		—		—
Outstanding, December 31, 2018		8,032,458		9.04		12.48		7.47		507,876
Vested and expected to vest at December 31, 2018		8,032,458		9.04		12.48		7.47		507,876
Exercisable at December 31, 2018		5,185,893		2.75		3.09		6.73		360,505

Schedule of Assumptions Used to Estimate Fair Values of Share Options Granted

11Share-based compensation (continued)

The following table presents assumptions used to estimate the fair values of share options granted for the year ended December 31, 2017 and 2018:

	2016		2017		2018
Risk-free interest rate	1.83% - 1.84%		2.27% - 2.41%		2.27% - 2.93%
Dividend yield	0%		0%		0%
Expected volatility	47.33% - 47.60%		46.33% - 47.15%		45.30% - 46.10%
Weighted average expected volatility	47.44%		46.66%		45.98%
Expected exercise multiple		2.5		2.5		2.5

(i)	Risk-free interest rate – The risk-free interest rate for periods within the contractual life of the options is based on the US Treasury yield curve in effect at the time of the grant for a term consistent with the contractual term of the awards.

(ii)	Dividend yield – The dividend yield is estimated based on the Company’s expected dividend policy over the expected term of the options.

(iii)

Expected volatility – Expected volatility is estimated based on the historical volatility of common shares of several comparable publicly-traded companies in the same industry.

(iv)	Expected exercise multiple – expected exercise multiple is estimated based on changes in expected intrinsic value of the option and the likelihood of early exercise by employees.

Summary of Restricted Share Units

A summary of the restricted share units for the year ended December 31, 2018 was stated below:

Restricted Share Units Granted to Employees and Directors	Number of Share Units		Weighted-Average Exercise Price		Weighted- Average grant-date Fair Value per Option		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
			RMB		RMB				RMB
Outstanding, December 31, 2017		—		—		—		—		—
Granted		12,550		—		54.69		9.68		907
Forfeited		—		—		—		—		—
Expired		—		—		—		—		—
Exercised		—		—		—		—		—
Cancelled		—		—		—		—		—
Outstanding, December 31, 2018		12,550		—		54.69		9.68		907
Vested and expected to vest at December 31, 2018		12,550		—		54.69		9.68		907
Exercisable at December 31, 2018		—		—		—		—		—

Summary of Total Compensation Costs Recognized

11Share-based compensation (continued)

Total compensation costs recognized for the year ended December 31, 2017 and 2018 were as follows:

	Year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Research and development		664		1,408		9,448		1,374
Sales and marketing		189		944		3,347		487
General and administrative		1,850		5,923		11,766		1,711
Total		2,703		8,275		24,561		3,572

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Summary of Profit / (Loss) Before Income Taxes

The Company’s profit/(loss) before income taxes consists of:

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Cayman Islands		(3,214	)		(10,584	)		6,622			964
British Virgin Islands		(4	)		(2	)		(25	)		(4	)
Hong Kong		563			(34	)		208			30
China		(54,817	)		(83,651	)		(72,972	)		(10,613	)
Total loss before income taxes		(57,472	)		(94,271	)		(66,167	)		(9,623	)

Summary of Composition of Income Tax Expense

The current and deferred portions of income tax expense included in the consolidated statements of comprehensive loss are as follows:

	As of December 31,
	2016			2017		2018
	RMB			RMB		RMB			US$
Current income tax expense		—			—		(35	)		(5	)
Deferred tax (expense)/benefit		(3,910	)		3,980		5			1
Total income tax (expense)/benefit		(3,910	)		3,980		(30	)		(4	)

Summary of Reconciliation Between Expenses of Income Taxes

Reconciliation between the expense of income taxes computed by applying the statutory tax rate to loss before income taxes and the actual provision for income taxes is as follows:

	As of December 31,
	2017			2018
	RMB			RMB			US$
Loss before income tax		(94,271	)		(66,167	)		(9,623	)
Income tax expense computed at PRC statutory rate (25%)		(23,569	)		(16,542	)		(2,408	)
International tax rate differential		2,650			(1,668	)		(243	)
Preferential tax rate		4,004			6,397			930
Deferred tax items tax rate differential		(4,951	)		(6,390	)		(929	)
Research and development super-deduction		(7,787	)		(21,559	)		(3,134	)
Non-deductible expenses		1,482			5,701			829
Outside basis differences		(7,475	)		—			—
Deferred tax expense		—			4,073			592
Changes in valuation allowance		31,666			30,018			4,367
Income tax expense/(benefit)		(3,980	)		30			4

Summary of Deferred Tax Assets and Liabilities

	As of December 31,
	2017			2018
	RMB			RMB			US$
Deferred tax assets, net
Provision for doubtful debts		866			2,463			358
Accrued expense		231			3,737			543
Net operating loss carry forward		54,079			78,985			11,489
Government grant related to assets		69			54			8
Fixed assets depreciation		—			14			2
Estimated liabilities		—			10			2
Valuation allowance		(55,245	)		(85,263	)		(12,401	)
Total deferred tax assets, net		—			—			—
Deferred tax liabilities
Fixed assets depreciation		5			—			—
Total deferred tax liabilities		5			—			—

Convertible Notes (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Summary of Principal Amount, Debt Issuance Costs and Derivative Liability

The principal amount, debt issuance costs and derivative liability as of December 31, 2018 was as follows:

	As of April 17, 2018			Charge to profit and loss			Foreign currency translation adjustment		As of December 31, 2018
	RMB			RMB			RMB		RMB			US$
Principal amount		219,699			—			20,513		240,212			34,937
Issuance costs		(8,436	)		—			—		(8,436	)		(1,227	)
Contingent redemption feature		(19,805	)		—			4,208		(15,597	)		(2,268	)
Convertible notes		191,458			—			24,721		216,179			31,442
Derivative liability		20,237			(21,302	)		1,065		—			—
Total		211,695			(21,302	)		25,786		216,179			31,442

Summary of Aggregate Future Principal Payments for the Convertible Notes

As of December 31, 2018, aggregate future principal payments for the Convertible Notes were as follows:

	RMB		US$
1 year (Including 1 year)		—		—
1 year to 2 years (Including 2 years)		—		—
2 years to 3 years (Including 3 years)		240,212		35,000
Total		240,212		35,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments Under Non-cancelable Operating Leases

As of December 31, 2018, future minimum payments under non-cancellable operating leases were as follows:

	RMB		US$
2019		13,387		1,947
2020		10,573		1,538
2021		4,613		671
2022 and thereafter		4,478		651
Total		33,051		4,807

Share Capital (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Basic and Diluted Loss Per Share

Basic and diluted loss per share is calculated as follows:

	For the year ended December 31, 2016			For the year ended December 31, 2017			For the year ended December 31, 2018
	Common shares			Common shares			Class A						Class B
	RMB			RMB			RMB			US$			RMB			US$
Numerator:
Net loss attributable to Class A and Class B common shareholders		(61,382	)		(90,291	)		(46,606	)		(6,779	)		(19,591	)		(2,848	)
Deduct: Accretion of redeemable convertible preferred shares		(12,427	)		(26,391	)		(16,963	)		(2,467	)		(7,131	)		(1,037	)
Net Loss attributable to common shareholders		(73,809	)		(116,682	)		(63,569	)		(9,246	)		(26,722	)		(3,885	)
Denominator:
Weighted average number of shares used in calculating basic and diluted loss per share		42,666,670			42,666,670			40,441,999			40,441,999			17,000,189			17,000,189
Basic and diluted loss per share		(1.73	)		(2.73	)		(1.57	)		(0.23	)		(1.57	)		(0.23	)

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Amount Due From Related Party

16.1 Amounts due from related parties

	As of December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Focus Axis Limited		2		17		—		—
KK Mobile Limited		26		40		—		—
Stable View Limited		2		17		—		—
Shenzhen Weixunyitong Information Technology Co., Ltd.		65		886		1,543		224
Guangzhou Tianlang Network Technology Co., Ltd.		—		300		1,305		190
President		—		—		1,716		250
Total amounts due from related parties		95		1,260		4,564		664

Schedule of Amount Due to Related Party

16.2 Amounts due to related parties

	As of December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Weidong Luo		5,649		5,649	—		—
Shenzhen Weixunyitong Information Technology Co., Ltd.		504		461		8,864		1,289
Guangzhou Tianlang Network Technology Co., Ltd.		200	—		—		—
Total amounts due to related parties		6,353		6,110		8,864		1,289

Schedule of Transactions With Related Parties

16	Related party transactions (continued)

16.3 Transactions with related parties

	For the year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Services provided to:
Shenzhen Weixunyitong Information Technology Co., Ltd.		344		2,752		1,002		142
Guangzhou Tianlang Network Technology Co., Ltd.	—			755		1,542		224
Total		344		3,507		2,544		366
Services received from:
Shenzhen Weixunyitong Information Technology Co., Ltd.		360		672		20,909		3,041
Office premises leased from:
Shenzhen Weixunyitong Information Technology Co., Ltd.		1,193		1,557		475		69
Marketing expense incurred:
Guangzhou Tianlang Network Technology Co., Ltd.		943	—		—		—
Total		2,496		2,229		21,384		3,110

Revenues (Tables)

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Schedule of Revenues

Revenues consist of the following:

	Year ended December 31,
	2016		2017		2018
	RMB		RMB		RMB		US$
Developer services		23,196		38,795		60,106		8,742
Data solutions
Targeted Marketing		43,149		221,153		572,796		83,310
Other vertical data solutions		3,977		24,761		81,239		11,816
Total data solutions		47,126		245,914		654,035		95,126
Total revenues		70,322		284,709		714,141		103,868

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of Changes in Fair Value of Redemption Feature Derivative Liability

The changes in fair value of the redemption feature derivative liability during fiscal years 2017 and 2018 are shown in the following table.

	Fair value measurements
	Quoted prices in active market for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)			Total
As of December 31, 2017 in RMB		—		—		—			—
Derivative liability						20,237			20,237
Foreign currency translation adjustment						1,065			1,065
Charge to profit and loss		—		—		(21,302	)		21,302
As of December 31, 2018 in RMB		—		—		—			—
As of December 31, 2018 in USD		—		—		—			—

Condensed Financial Information of the Parent Company (Tables)

12 Months Ended

Dec. 31, 2018

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Condensed Balance Sheets

	As of December 31,
	2017			2018
	RMB			RMB			US$
ASSETS:
Current assets:
Cash and cash equivalents		118,429			238,236			34,650
Due from the entities within the Group		6,603			7,030			1,022
Prepayments		—			2,439			355
Interest receivables		—			89			13
Amounts due from related parties		28			—			—
Other receivables		—			1,717			251
Total current assets		125,060			249,511			36,291
Non-current assets:
Long-term investments		126,616			590,752			85,921
Intangible assets		—			93			14
Total non-current assets		126,616			590,845			85,935
Total assets		251,676			840,356			122,226
LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS DEFICIT
Current liabilities:
Accrued liabilities and other current liabilities		3,072			11,542			1,679
Due to the entities within the Group		702			710			103
Amounts due to related parties		5,649			—			—
Total current liabilities		9,423			12,252			1,782
Non-current liabilities:
Deferred revenue - non-current		—			10,265			1,493
Convertible notes		—			216,179			31,442
Total non-current liabilities		—			226,444			32,935
Total liabilities		9,423			238,696			34,717
Mezzanine equity
Series A contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 11,111,120 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		26,979			—			—
Series B contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 7,936,510 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		52,723			—			—
Series C contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 4,999,540 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		168,317			—			—
Series D contingently redeemable convertible preferred shares (par value of US$0.0001 and US$ nil per share as of December 31, 2017 and 2018; 5,559,487 and nil shares authorized, issued and outstanding as of December 31, 2017 and 2018, respectively)		218,618			—			—
Total mezzanine equity		466,637			—			—
Shareholders’ deficit
Common shares (par value of US$0.0001 and nil per share as of December 31, 2017 and 2018; 470,393,343 and 50,000,000 shares authorized as of December 31, 2017 and 2018, 42,666,670 and nil shares issued and outstanding as of December 31, 2017 and 2018, respectively)		26			—			—
Class A common shares (par value of nil and US$0.0001 per share as of December 31, 2017 and 2018; nil and 4,920,000,000 shares authorized as of December 31, 2017 and 2018, nil and 59,547,823 shares issued and outstanding as of December 31, 2017 and 2018, respectively)		—			37			5
Class B common shares (par value of nil and US$0.0001 per share as of December 31, 2017 and 2018; nil and 30,000,000 shares authorized as of December 31, 2017 and 2018, nil and 17,000,189 shares issued and outstanding as of December 31, 2017 and 2018)		—			11			2
Treasury shares (nil and 46,303 class A common shares as of December 31, 2017 and 2018, respectively)		—			(3,165	)		(460	)
Additional paid-in capital		13,689			944,500			137,372
Accumulated deficit		(234,810	)		(348,123	)		(50,632	)
Accumulated other comprehensive loss		(3,289	)		8,400			1,221
Total shareholders’ deficit		(224,384	)		601,660			87,508
Total liabilities, mezzanine equity and shareholders’ deficit		251,676			840,356			122,226

Condensed Statements of Comprehensive Loss

21	Condensed financial information of the parent company (continued)

Condensed Statements of Comprehensive Loss

	As of December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Revenues		—			—			—			—
Cost of Revenues		—			—			—			—
Gross profit		—			—			—			—
Operating expenses
Research and development		—			—			—			—
Sales and marketing		—			—			—			—
General and administrative		(2,302	)		(10,076	)		(11,941	)		(1,737	)
Share of losses of subsidiaries and the VIE		(58,167	)		(79,916	)		(72,750	)		(10,581	)
Total operating expenses		(60,469	)		(89,992	)		(84,691	)		(12,318	)
Loss from operations		(60,469	)		(89,992	)		(84,691	)		(12,318	)
Foreign exchange loss, net		(961	)		(339	)		(186	)		(27	)
Interest income		48			18			3,013			438
Interest expense		—			—			(6,599	)		(960	)
Other income		—			22			22,266			3,238
Loss before income taxes		(61,382	)		(90,291	)		(66,197	)		(9,629	)
Income tax expenses		—			—			—			—
Net Loss		(61,382	)		(90,291	)		(66,197	)		(9,629	)
Accretion of contingently redeemable convertible preferred shares		(12,427	)		(26,391	)		44,451			6,465
Net loss attributable to common share holders		(73,809	)		(116,682	)		(21,746	)		(3,164	)
Other comprehensive income (loss)
Foreign currency translation adjustments		1,896			(7,563	)		29,510			4,292
Total other comprehensive income (loss), net of tax		1,896			(7,563	)		29,510			4,292
Comprehensive loss		(59,486	)		(97,854	)		(36,687	)		(5,337	)

Condensed Statements of Cash Flows

	For the year ended December 31,
	2016			2017			2018
	RMB			RMB			RMB			US$
Net cash used in operating activities		(2,311	)		(744	)		16,052			2,335
Net cash used in investing activities		(77,193	)		(157,412	)		(535,995	)		(77,957	)
Net cash from financing activities		134,348			217,446			614,884			89,431
Effect of exchange rate changes		2,649			(7,695	)		24,866			3,617
Net increase in cash and cash equivalents		57,493			51,595			119,807			17,426
Cash and cash equivalents and restricted cash at the beginning of year		9,341			66,834			118,429			17,224
Cash and cash equivalents and restricted cash at the end of year		66,834			118,429			238,236			34,650

Organization and Principal Activities - Summary of Assets and Liabilities of VIE (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2015 CNY (¥)
Current assets:
Cash and cash equivalents	¥ 576,562	$ 83,857	¥ 208,161	$ 30,276	¥ 103,168	¥ 37,570
Restricted cash	115	17	115
Accounts receivable	141,911	20,640	49,594
Amounts due from related parties	4,564	664	1,260		95
Total current assets	803,730	116,897	293,358
Non-current assets:
Long-term investments	79,696	11,591	10,980
Property and equipment, net	92,874	13,508	53,023
Intangible assets, net	1,531	223	283
Total non-current assets	188,338	27,393	66,092
Total assets	992,068	144,290	359,450
Current liabilities:
Accounts payable	18,811	2,736	8,340
Deferred revenue and customer deposits	33,067	4,809	28,921
Accrued liabilities and other current liabilities	76,666	11,151	52,639
Amount due to related parties	8,864	1,289	6,110		¥ 6,353
Total current liabilities	163,824	23,827	116,646
Non-current liabilities:
Other non-current liabilities	140	20	216
Deferred tax liabilities			5
Deferred revenue and customer deposits	10,265	1,493	330
Total non-current liabilities	226,584	32,955	551
Total liabilities	390,408	56,782	117,197
VIE
Current assets:
Cash and cash equivalents	31,763	4,620	49,853
Restricted cash	115	17	115
Accounts receivable	141,705	20,609	49,561
Prepayments and other current assets	64,532	9,386	29,637
Amounts due from the Company and its subsidiaries	3,965	577	3,806
Amounts due from related parties	2,848	414	1,186
Total current assets	244,928	35,623	134,158
Non-current assets:
Long-term investments	71,512	10,401	10,000
Other receivables-non current	2,529	368	1,354
Property and equipment, net	46,271	6,730	24,258
Intangible assets, net	1,406	204	283
Long-term prepayment	11,000	1,600
Total non-current assets	132,718	19,303	35,895
Total assets	377,646	54,926	170,053
Current liabilities:
Accounts payable	18,683	2,717	8,340
Deferred revenue and customer deposits	55,625	8,091	48,085
Accrued liabilities and other current liabilities	59,556	8,662	31,631
Amounts due to the Company and its subsidiaries	15,534	2,259	39,861
Amount due to related parties	8,864	1,289	459
Total current liabilities	158,262	23,018	128,376
Non-current liabilities:
Amounts due to the Company and its subsidiaries	240,000	34,907	60,000
Other non-current liabilities	140	20	216
Deferred tax liabilities	0	0	5
Deferred revenue and customer deposits	0	0	330
Total non-current liabilities	240,140	34,927	60,551
Total liabilities	¥ 398,402	$ 57,945	¥ 188,927

Organization and Principal Activities - Summary of Results of Operations and Cash Flows of VIE (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Variable Interest Entity [Line Items]
Cost of revenues	¥ (517,074)	$ (75,205)	¥ (213,370)	¥ (47,722)
Net income/(loss)	(66,197)	(9,627)	(90,291)	(61,382)
Net cash used in operating activities	(97,925)	(14,241)	(75,532)	(42,152)
Net cash used in investing activities	(139,206)	(20,246)	(28,644)	(29,928)
Net cash provided by financing activities	614,884	89,431	217,446	135,348
VIE
Variable Interest Entity [Line Items]
Revenues	709,594	103,206	284,348	70,148
Cost of revenues	(499,589)	(72,662)	(206,789)	(47,559)
Net income/(loss)	(16,785)	(2,441)	(40,003)	18,681
Net cash used in operating activities	(68,316)	(9,936)	(51,016)	7,590
Net cash used in investing activities	(104,675)	(15,224)	¥ (10,000)
Net cash provided by financing activities	¥ 154,901	$ 22,529		¥ 1,000

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Mar. 01, 2017 USD ($) shares	Dec. 31, 2018 CNY (¥) Supplier Segment ¥ / $ shares	Dec. 31, 2018 USD ($) Supplier Segment shares	Dec. 31, 2017 CNY (¥) Supplier	Dec. 31, 2017 USD ($) Supplier	Dec. 31, 2016 CNY (¥)	Dec. 31, 2018 USD ($) ¥ / $	Nov. 20, 2018 USD ($)	Apr. 17, 2018 CNY (¥)	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Foreign currency exchange rate \| ¥ / $		6.8755					6.8755
Impairment of long-lived assets other than goodwill		¥ 0		¥ 0		¥ 0
Debt issuance costs		¥ 8,436,000					$ 1,227,000		¥ 8,436,000
Value added tax percentage				6.00%	6.00%
Share split, ratio	0.1
Share split, description		1 for 10 share split	1 for 10 share split
Share repurchased cash consideration		¥ 3,165,000
Research and development cost, capitalized		0
Advertising expenses		¥ 6,697,000	$ 974,000	¥ 5,277,000		10,377,000
Profit sharing program, recognized period		5 years	5 years
Capital leases		¥ 0
Employee defined contribution plan expense incurred		¥ 11,301,000	$ 1,644,000	12,121,000		5,455,000
Appreciation of the US$ against RMB, percent		4.79%	4.79%
Number of reportable segment \| Segment		1	1
Revenues		¥ 714,141,000	$ 103,868,000	¥ 284,709,000		¥ 70,322,000
Product Concentration Risk \| Suppliers
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		81.30%	81.30%	50.90%	50.90%
Advertising
Summary Of Significant Accounting Policies [Line Items]
Number of suppliers \| Supplier		3	3	3	3
CHINA
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents, restricted cash and short-term investments		¥ 331,374,000		¥ 82,609,000			48,198,000
Outside China
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents, restricted cash and short-term investments		¥ 245,303,000					35,678,000			$ 19,232,000
Maximum
Summary Of Significant Accounting Policies [Line Items]
Revenues \| $					$ 1,070,000,000
American Depositary Shares
Summary Of Significant Accounting Policies [Line Items]
Share repurchased under repurchase plan \| shares	69,455	69,455	69,455
Share repurchased cash consideration \| $	$ 468,000
American Depositary Shares \| Maximum
Summary Of Significant Accounting Policies [Line Items]
Share repurchase plan, authorized amount \| $	$ 10,000,000							$ 10,000,000
Class A Common Shares
Summary Of Significant Accounting Policies [Line Items]
Share repurchased under repurchase plan \| shares	46,303	46,303	46,303
Convertible Notes
Summary Of Significant Accounting Policies [Line Items]
Debt issuance costs		¥ 8,436,000					$ 1,275,000

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	over the shorter of lease terms or estimated useful lives of the assets
Minimum \| Computer Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Minimum \| Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Maximum \| Computer Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Maximum \| Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years

Accounts Receivable, Net - Schedule of Accounts Receivable (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Receivables [Abstract]
Accounts receivable	¥ 151,219	$ 21,994	¥ 53,056
Less: allowance for doubtful accounts	(9,308)	(1,354)	(3,462)
Total accounts receivable, net	¥ 141,911	$ 20,640	¥ 49,594

Accounts Receivable, Net - Schedule of Movement in Allowance for Doubtful Accounts (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Receivables [Abstract]
Beginning balance	¥ 3,462	$ 504	¥ 1,035
Provisions	6,389	929	2,427
Write-offs	(543)	(79)
Ending balance	¥ 9,308	$ 1,354	¥ 3,462

Prepayment and Other Current Assets - Schedule of Prepayment and Other Current Assets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid media cost	¥ 54,937	$ 7,990	¥ 19,610
Prepaid service fee	6,804	989	1,762
Others	18,837	2,740	12,856
Total prepayment and other current assets	¥ 80,578	$ 11,719	¥ 34,228

Property and Equipment, Net - Schedule of Property and Equipment (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Property Plant And Equipment [Line Items]
Less: Accumulated depreciation	¥ (30,576)	$ (4,447)	¥ (13,739)
Property and equipment, net	92,874	13,508	53,023
Office Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	4,920	716	2,647
Computer Equipment and Servers
Property Plant And Equipment [Line Items]
Property and equipment, gross	111,274	16,184	63,326
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	¥ 7,256	$ 1,055	¥ 789

Property and Equipment, Net - Additional Information (Details) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2016 USD ($)
Property Plant And Equipment [Abstract]
Fixed assets impairment charges		$ 0		$ 0		$ 0
Depreciation of property and equipment	¥ 18,084	$ 2,630,000	¥ 8,805		¥ 3,433

Intangible Assets - Schedule of Intangible Assets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Goodwill And Intangible Assets Disclosure [Abstract]
Computer software and systems	¥ 1,874	$ 273	¥ 319
Less: Accumulated amortization	(343)	(50)	(36)
Total intangible assets, net	¥ 1,531	$ 223	¥ 283

Intangible Assets - Additional Infomation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment charges	¥ 0		¥ 0	¥ 0
Amortization of intangible assets	307,000	$ 45	35,000	¥ 0
Intangible assets with an indefinite useful life	¥ 0		¥ 0

Intangible Assets - Schedule of Estimated Amortization Expense Related to the Existing Intangible Assets (Details) - Dec. 31, 2018 ¥ in Thousands, $ in Thousands	CNY (¥)	USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
For the year ending December 31, 2019	¥ 749	$ 109
2020	464	67
2021	¥ 318	$ 47

Long-Term Investments - Additional Information (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Schedule Of Investments [Line Items]
Cost method investments	¥ 79,696	¥ 10,980		$ 11,591
Impairment losses	¥ 0	¥ 0	¥ 0
Zhuoxuan
Schedule Of Investments [Line Items]
Percentage of share acquired	5.93%			5.93%
Cost method investments	¥ 5,438			$ 792
Mengxiang
Schedule Of Investments [Line Items]
Percentage of share acquired	13.80%			13.80%
Cost method investments	¥ 21,512			$ 3,134
Qianhai
Schedule Of Investments [Line Items]
Percentage of share acquired	10.00%			10.00%
Cost method investments	¥ 40,000			$ 5,828
Skymind
Schedule Of Investments [Line Items]
Cost method investments	¥ 1,716		¥ 980	$ 250		$ 150
Percentage of company held share capital			1.19%			1.19%
Shuwei
Schedule Of Investments [Line Items]
Percentage of share acquired	4.27%	6.25%		4.27%	6.25%
Cost method investments		¥ 10,000			$ 1,457

Deferred Revenue and Customer Deposits (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)
Revenue Recognition And Deferred Revenue [Abstract]
Deferred revenue	¥ 33,067	$ 4,809	¥ 28,921
Customer deposits	26,416	3,842	20,636	$ 3,001	¥ 6,064
Total deferred revenue and customer deposits — current	59,483	8,651	49,557
Deferred revenue — non-current	¥ 10,265	$ 1,493	¥ 330

Deferred Revenue and Customer Deposits - Roll Forward of Customer Deposits (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Revenue Recognition And Deferred Revenue [Abstract]
Balance at beginning of year	¥ 20,636	$ 3,001	¥ 6,064
Cash received from customers during the year	407,630	59,287	129,555
Revenue recognized during the year	(397,488)	(57,812)	(112,770)
Refunds paid during the year	(4,362)	(634)	(2,213)
Balance at end of year	¥ 26,416	$ 3,842	¥ 20,636

Accrued Liabilities and Other Current Liabilities - Schedule of Accrued Liabilities and Other Current Liabilities (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Payables And Accruals [Abstract]
Accrued payroll and welfare payables	¥ 51,607	$ 7,506	¥ 38,704
Other taxes and surcharge	11,277	1,640	2,676
Service fees	11,130	1,619	560
Acquisition of fixed assets	104	15	9,731
Others	2,548	371	968
Total accrued liabilities and other current liabilities	¥ 76,666	$ 11,151	¥ 52,639

Contingently Redeemable Convertible Preferred Shares - Additional information (Details) $ / shares in Units, $ in Thousands							12 Months Ended
	Oct. 05, 2017 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) $ / shares shares	Apr. 01, 2016 USD ($) $ / shares shares	May 13, 2015 USD ($) $ / shares shares	Jan. 21, 2015 USD ($) $ / shares shares	Nov. 18, 2014 USD ($) $ / shares shares	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 $ / shares	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Temporary Equity [Line Items]
Preferred shares dividends declared \| $ / shares								$ 0
Common shares issued upon the conversion of the preferred shares							50.00%	50.00%
Accretion charge \| ¥							¥ 24,094,000		¥ 26,391,000
Preferred shares to common shares, conversion date							Jul. 26, 2018
Maximum
Temporary Equity [Line Items]
Equity classified preferred shares modification percentage							10.00%	10.00%
Minimum
Temporary Equity [Line Items]
Equity classified preferred shares modification percentage							10.00%	10.00%
Series C Preferred Share Agreement
Temporary Equity [Line Items]
Performance ratchet description							Performance Ratchet” whereby if the Company’s PRC GAAP audited revenue was less than (i) RMB80,000 in 2016, or (ii) RMB120,000 in 2017, Weidong Luo and the Company shall compensate the Series C investors in accordance to the specified formula
Audited revenue required for compensation to investors \| ¥									¥ 120,000	¥ 80,000
Liquidation Preference
Temporary Equity [Line Items]
Acquisition voting power							50.00%	50.00%
Mandra iBased Limited
Temporary Equity [Line Items]
Common shares issued upon the conversion of the preferred shares							20.00%	20.00%
Series A-1 Preferred Shares
Temporary Equity [Line Items]
Shares issued per share \| $ / shares						$ 0.36
Total consideration \| $						$ 2,000
Series A-1 Preferred Shares \| IDG-Accel China Growth Fund III L.P
Temporary Equity [Line Items]
Shares issued						5,187,780
Series A-1 Preferred Shares \| IDG-Accel China III Investors L.P
Temporary Equity [Line Items]
Shares issued						367,780
Series A-2 Preferred Shares
Temporary Equity [Line Items]
Shares issued per share \| $ / shares					$ 0.36
Total consideration \| $					$ 2,000
Series A-2 Preferred Shares \| IDG-Accel China Growth Fund III L.P
Temporary Equity [Line Items]
Shares issued					2,593,890
Series A-2 Preferred Shares \| IDG-Accel China III Investors L.P
Temporary Equity [Line Items]
Shares issued					183,890
Series A-2 Preferred Shares \| Elite Bright International Limited
Temporary Equity [Line Items]
Shares issued					1,388,890
Series A-2 Preferred Shares \| Mandra iBase Limited
Temporary Equity [Line Items]
Shares issued					1,388,890
Series B Preferred Share
Temporary Equity [Line Items]
Shares issued per share \| $ / shares				$ 0.95
Total consideration \| $				$ 7,500
Series B Preferred Share \| IDG-Accel China Growth Fund III L.P
Temporary Equity [Line Items]
Shares issued				494,070
Series B Preferred Share \| IDG-Accel China III Investors L.P
Temporary Equity [Line Items]
Shares issued				35,030
Series B Preferred Share \| Elite Bright International Limited
Temporary Equity [Line Items]
Shares issued				529,100
Series B Preferred Share \| Mandra iBase Limited
Temporary Equity [Line Items]
Shares issued				529,100
Series B Preferred Share \| Greatest Investments Limited
Temporary Equity [Line Items]
Shares issued				6,349,210
Series C-1 Preferred Shares
Temporary Equity [Line Items]
Shares issued per share \| $ / shares			$ 4.73
Total consideration \| $			$ 11,111
Series C-1 Preferred Shares \| Greatest Investments Limited
Temporary Equity [Line Items]
Shares issued			235,160
Series C-1 Preferred Shares \| Shenzhen Guohai Chuangxin Investment Management Limited Corporation
Temporary Equity [Line Items]
Shares issued			2,116,400
Series C Two Contingent Redeemable Convertible Preferred Shares
Temporary Equity [Line Items]
Shares issued per share \| $ / shares		$ 4.73
Total consideration \| $		$ 12,000
Series C Two Contingent Redeemable Convertible Preferred Shares \| Mandra iBase Limited
Temporary Equity [Line Items]
Shares issued		634,920
Series C Two Contingent Redeemable Convertible Preferred Shares \| T.C.L. Industries Holdings (H.K.) Ltd
Temporary Equity [Line Items]
Shares issued		1,693,120
Series C Two Contingent Redeemable Convertible Preferred Shares \| Genesis Ventures Limited
Temporary Equity [Line Items]
Shares issued		211,640
Series C Preferred Shares
Temporary Equity [Line Items]
Liquidation preference as percentage of issue price							100.00%
Liquidation preference							plus an annual simple return of 10% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series B and A preferred shares
Series C Preferred Shares \| Liquidation Preference
Temporary Equity [Line Items]
Preferred stock annual simple return percentage							10.00%
Series B Preferred Shares
Temporary Equity [Line Items]
Liquidation preference as percentage of issue price							125.00%
Liquidation preference							After the payment to the holders of Series C preferred shares, the holders of Series B preferred shares are entitled to receive an amount equal to 125% of the Series B Issue Price, plus an annual compounded return of 6% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series A preferred shares and the common shareholders of the Company.
Series B Preferred Shares \| Liquidation Preference
Temporary Equity [Line Items]
Preferred stock annual compound return percentage							600.00%
Series A Preferred Shares
Temporary Equity [Line Items]
Liquidation preference as percentage of issue price							150.00%
Liquidation preference							After the payment to the holders of Series C preferred shares, the holders of Series B preferred shares are entitled to receive an amount equal to 125% of the Series B Issue Price, plus an annual compounded return of 6% accrued thereon and plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series A preferred shares and the common shareholders of the Company.
Series A Preferred Shares \| Liquidation Preference
Temporary Equity [Line Items]
Preferred stock annual compound return percentage							8.00%
Redeemable Convertible Preferred Shares
Temporary Equity [Line Items]
Preferred stock initial conversion ratio							100.00%
Series D Preferred Shares
Temporary Equity [Line Items]
Shares issued per share \| $ / shares	$ 5.40
Total consideration \| $	$ 30,000
Liquidation preference as percentage of issue price							115.00%
Liquidation preference							The holders of Series D preferred shares are entitled to receive an amount equal to 115% of the Series D Issue Price, plus all declared but unpaid dividend, in preference to any distribution to the holders of the Series C, B and A preferred shares and the common shareholders of the Company.
Series D Preferred Shares \| Fidelity Investment Funds
Temporary Equity [Line Items]
Shares issued	28,062
Series D Preferred Shares \| Fidelity China Special Situations PLC
Temporary Equity [Line Items]
Shares issued	2,441,572
Series D Preferred Shares \| Fidelity Funds
Temporary Equity [Line Items]
Shares issued	3,089,853

Contingently Redeemable Convertible Preferred Shares - Schedule of Movement in Carrying Value of Convertible Preferred Shares (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Beginning balance	¥ 466,637	¥ 220,539
Issuance cost of preferred shares		(7,223)
Accretion of Preferred Shares	24,094	26,391
Redemption of Preferred Shares	(57,234)
Concertion to Common Shares	(433,497)
Ending balance		466,637
Series A
Class Of Stock [Line Items]
Beginning balance	26,979	26,804
Accretion of Preferred Shares	1,463	175
Concertion to Common Shares	(28,442)
Ending balance		26,979
Series B
Class Of Stock [Line Items]
Beginning balance	52,723	52,044
Accretion of Preferred Shares	4,137	679
Concertion to Common Shares	(56,860)
Ending balance		52,723
Series C
Class Of Stock [Line Items]
Beginning balance	168,317	141,691
Issuance of preferred shares		20,571
Accretion of Preferred Shares	7,441	6,055
Redemption of Preferred Shares	(57,234)
Concertion to Common Shares	(118,524)
Ending balance		168,317
Series D
Class Of Stock [Line Items]
Beginning balance	218,618
Issuance of preferred shares		206,359
Issuance cost of preferred shares		(7,223)
Accretion of Preferred Shares	11,053	19,482
Concertion to Common Shares	¥ (229,671)
Ending balance		¥ 218,618

Share-Based Compensation - Additional Information (Details) ¥ / shares in Units, $ / shares in Units, ¥ in Thousands, $ in Thousands			12 Months Ended
	Mar. 01, 2017 shares	Jul. 23, 2014 shares	Dec. 31, 2018 CNY (¥) ¥ / shares shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2018 USD ($) shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of awards vested expenses recognized			¥ 24,561	$ 3,572	¥ 8,275	¥ 2,703
Share Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of awards vested expenses recognized			24,561	$ 3,572	¥ 8,275	¥ 2,703
Unrecognized share-based compensation expense			¥ 64,099				$ 9,323
Restricted Share Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense estimated weighted-average period			1 year	1 year
Weighted average grant-date fair value per share, granted \| (per share)			¥ 54.69	$ 7.95
Unrecognized share-based compensation cost			¥ 447				$ 68
Maximum \| Share Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense estimated weighted-average period			4 years	4 years
Minimum \| Share Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized share-based compensation expense estimated weighted-average period			3 years	3 years
2014 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period		4 years
Common shares reserved for issuance		5,500,000
Share available for grant			2,420				2,420
2014 Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards expiration period		10 years
2017 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period	4 years
Common shares reserved for issuance	6,015,137
Share available for grant			3,467,708				3,467,708
2017 Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards expiration period	10 years
2014 and 2017 Plans
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards expiration period			10 years	10 years
2014 and 2017 Plans \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period			4 years	4 years
2014 and 2017 Plans \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period			1 year	1 year

Share-Based Compensation - Summary of Share Option Activity (Details) - CNY (¥) ¥ / shares in Units, ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding, Beginning Balance	6,366,146	5,472,031
Number of Options, Granted	1,736,390	894,115
Number of Options, Forfeited	55,520
Number of Options, Cancelled	14,558
Number of Options, Outstanding, Ending Balance	8,032,458	6,366,146	5,472,031
Number of Options, Vested and expected to vest	8,032,458	6,366,146
Number of Options, Exercisable	5,185,893
Weighted-Average Exercise Price, Outstanding, Beginning Balance	¥ 4.33	¥ 2.32
Weighted-Average Exercise Price, Granted	26.68	16.29
Weighted-Average Exercise Price, Forfeited	26.55
Weighted-Average Exercise Price, Cancelled	6.56
Weighted-Average Exercise Price, Outstanding, Ending Balance	9.04	4.33	¥ 2.32
Weighted-Average Exercise Price, Vested and expected to vest	9.04	4.33
Weighted-Average Exercise Price, Exercisable	2.75
Weighted- Average grant-date Fair Value per Option, Outstanding, Beginning Balance	3.31	2.13
Weighted- Average grant-date Fair Value per Option, Granted	45.72	10.34
Weighted- Average grant-date Fair Value per Option, Forfeited	24.69
Weighted- Average grant-date Fair Value per Option, Cancelled	1.87
Weighted- Average grant-date Fair Value per Option, Outstanding, Ending Balance	12.48	3.31	¥ 2.13
Weighted- Average grant-date Fair Value per Option, Vested and expected to vest	12.48	¥ 3.31
Weighted- Average grant-date Fair Value per Option, Exercisable	¥ 3.09
Weighted Average Remaining Contractual Term (Years), Outstanding	7 years 5 months 19 days	7 years 2 months 15 days	7 years 10 months 20 days
Weighted Average Remaining Contractual Term (Years), Vested and expected to vest	7 years 5 months 19 days	7 years 2 months 15 days
Weighted Average Remaining Contractual Term (Years), Exercisable	6 years 8 months 23 days
Aggregate Intrinsic Value, Outstanding	¥ 507,876	¥ 95,559	¥ 34,255
Aggregate Intrinsic Value, Vested and expected to vest	507,876	¥ 95,559
Aggregate Intrinsic Value, Exercisable	¥ 360,505

Share-Based Compensation - Schedule of Assumptions Used to Estimate Fair Values of Share Options Granted (Details) - ¥ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate, minimum	2.27%	2.27%	1.83%
Risk-free interest rate, maximum	2.93%	2.41%	1.84%
Dividend yield	0.00%	0.00%	0.00%
Expected volatility, minimum	45.29%	46.33%	47.33%
Expected volatility, maximum	46.15%	47.15%	47.60%
Weighted average expected volatility	45.98%	46.66%	47.44%
Expected exercise multiple	¥ 2.5	¥ 2.5	¥ 2.5

Share-Based Compensation - Summary of Restricted Share Units (Details) - Restricted Share Units - Employees and Directors ¥ / shares in Units, ¥ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥) ¥ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Share Units, Granted \| shares	12,550
Number of Share Units, Outstanding, December 31, 2018 \| shares	12,550
Number of Share Units, Vested and expected to vest at December 31, 2018 \| shares	12,550
Weighted-Average grant-date Fair Value per Option, Granted \| ¥ / shares	¥ 54.69
Weighted-Average grant-date Fair Value per Option, Outstanding, December 31, 2018 \| ¥ / shares	54.69
Weighted-Average grant-date Fair Value per Option, Vested and expected to vest at December 31, 2018 \| ¥ / shares	¥ 54.69
Weighted Average Remaining Contractual Term (Years), Granted	8 months 4 days
Weighted Average Remaining Contractual Term (Years), Outstanding, December 31, 2018	8 months 4 days
Weighted Average Remaining Contractual Term (Years), Vested and expected to vest at December 31, 2018	8 months 4 days
Aggregate Intrinsic Value, Granted \| ¥	¥ 907
Aggregate Intrinsic Value, Outstanding, December 31, 2018 \| ¥	907
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2018 \| ¥	¥ 907

Share-Based Compensation - Summary of Total Compensation Costs Recognized (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	¥ 24,561	$ 3,572	¥ 8,275	¥ 2,703
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	9,448	1,374	1,408	664
Sales and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	3,347	487	944	189
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	¥ 11,766	$ 1,711	¥ 5,923	¥ 1,850

Income Taxes - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016	Dec. 31, 2018 USD ($)
Income Tax Disclosure [Line Items]
Deferred tax assets related to net operating loss carry forwards	¥ 78,985,000	¥ 54,079,000		$ 11,489
Dividend withholding tax	0	0
Undistributed earnings	0	0
Interest and penalties related to an uncertain tax position	¥ 0	¥ 0
Income tax examination, description	In general, the PRC tax authorities have up to five years to conduct examinations of the tax filings of the Company’s PRC subsidiary and the VIE. Accordingly, the PRC tax filings from 2013 through 2018 remain open to examination by the respective tax authorities.
Minimum
Income Tax Disclosure [Line Items]
Open tax examination year	2013
Maximum
Income Tax Disclosure [Line Items]
Open tax examination year	2018
VIE \| Minimum
Income Tax Disclosure [Line Items]
Deferred tax assets operating loss carry forwards expiration year	2019
VIE \| Maximum
Income Tax Disclosure [Line Items]
Deferred tax assets operating loss carry forwards expiration year	2028
WFOE \| Minimum
Income Tax Disclosure [Line Items]
Deferred tax assets operating loss carry forwards expiration year	2019
WFOE \| Maximum
Income Tax Disclosure [Line Items]
Deferred tax assets operating loss carry forwards expiration year	2023
Hong Kong
Income Tax Disclosure [Line Items]
Effective profits tax rate	16.50%
PRC
Income Tax Disclosure [Line Items]
Effective statutory enterprise income tax rate	25.00%	25.00%	25.00%
Effective preferential income tax rate	15.00%
Preferential income tax rate, effective period	3 years
PRC \| VIE
Income Tax Disclosure [Line Items]
Effective preferential income tax rate	15.00%	15.00%
PRC \| WFOE
Income Tax Disclosure [Line Items]
Effective statutory enterprise income tax rate	25.00%

Income Taxes - Summary of Profit / (Loss) Before Income Taxes (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Income Tax Disclosure [Line Items]
Total loss before income taxes	¥ (66,167)	$ (9,623)	¥ (94,271)	¥ (57,472)
Cayman Islands
Income Tax Disclosure [Line Items]
Total loss before income taxes	6,622	964	(10,584)	(3,214)
British Virgin Islands
Income Tax Disclosure [Line Items]
Total loss before income taxes	(25)	(4)	(2)	(4)
Hong Kong
Income Tax Disclosure [Line Items]
Total loss before income taxes	208	30	(34)	563
China
Income Tax Disclosure [Line Items]
Total loss before income taxes	¥ (72,972)	$ (10,613)	¥ (83,651)	¥ (54,817)

Income Taxes - Summary of Composition of Income Tax Expense (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Income Tax Disclosure [Abstract]
Current income tax expense	¥ (35)	$ (5)
Deferred tax (expense)/benefit	5	1	¥ 3,980	¥ (3,910)
Total income tax (expense)/benefit	¥ (30)	$ (4)	¥ 3,980	¥ (3,910)

Income Taxes - Summary of Reconciliation Between Expenses of Income Taxes (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Income Tax Disclosure [Abstract]
Total loss before income taxes	¥ (66,167)	$ (9,623)	¥ (94,271)	¥ (57,472)
Income tax expense computed at PRC statutory rate	(16,542)	(2,408)	(23,569)
International tax rate differential	(1,668)	(243)	2,650
Preferential tax rate	6,397	930	4,004
Deferred tax items tax rate differential	(6,390)	(929)	(4,951)
Research and development super-deduction	(21,559)	(3,134)	(7,787)
Non-deductible expenses	5,701	829	1,482
Outside basis differences			(7,475)
Deferred tax expense	4,073	592
Changes in valuation allowance	30,018	4,367	31,666
Income tax expense/(benefit)	¥ 30	$ 4	¥ (3,980)	¥ 3,910

Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
Deferred tax assets, net
Provision for doubtful debts	¥ 2,463	$ 358	¥ 866
Accrued expense	3,737	543	231
Net operating loss carry forward	78,985	11,489	54,079
Government grant related to assets	54	8	69
Fixed assets depreciation	14	2
Estimated liabilities	10	2
Valuation allowance	¥ (85,263)	$ (12,401)	(55,245)
Deferred tax liabilities
Fixed assets depreciation			5
Total deferred tax liabilities			¥ 5

Convertible Notes - Additional Information (Details) $ / shares in Units, ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($) $ / shares	Apr. 17, 2018 CNY (¥)	Apr. 17, 2018 USD ($) $ / shares
Convertible Notes [Line Item]
Aggregate principal amount		¥ 240,212	$ 34,937	¥ 219,699
Initial offering period	no qualified IPO were to occur within two years of the issue date, the outstanding obligation at their principal amount
Percentage of internal rate of return	8.00%
Simple interest on principal		15.00%	15.00%
Interest on internal rate of return per annum	15.00%
Debt issuance costs		¥ 8,436	$ 1,227	¥ 8,436
Derivative liability			3,224
Change in fair value of current earnings	$ 3,224
Debt issuance costs, net		¥ 8,436	$ 1,275
Effective interest rate		4.69%	4.69%
BCF
Convertible Notes [Line Item]
Issuance price \| $ / shares			$ 11.76
Fair value per ordinary share \| $ / shares			$ 9.87
Zero Coupon Convertible Notes (the “Convertible Notes”) Due 2021
Convertible Notes [Line Item]
Conversion price per share \| $ / shares					$ 11.76
Debt issuance costs			$ 1,275
Zero Coupon Convertible Notes (the “Convertible Notes”) Due 2021 \| Existing Investor
Convertible Notes [Line Item]
Aggregate principal amount					$ 35,000

Convertible Notes - Summary of Principal Amount, Debt Issuance Costs and Derivative Liability (Details) ¥ in Thousands, $ in Thousands	8 Months Ended	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Apr. 17, 2018 CNY (¥)	Dec. 31, 2017 CNY (¥)
Convertible Notes [Line Item]
Principal amount	¥ 240,212	¥ 240,212		$ 34,937	¥ 219,699
Issuance costs	(8,436)	(8,436)		(1,227)	(8,436)
Contingent redemption feature	(15,597)	(15,597)		(2,268)	(19,805)
Convertible notes	216,179	216,179		31,442	191,458
Derivative liability					20,237
Total	216,179	216,179		$ 31,442	¥ 211,695	¥ 0
Charge to profit and loss	(21,302)	(21,302)	$ (3,098)
Foreign Currency Translation Adjustment
Convertible Notes [Line Item]
Principal amount	20,513	20,513
Contingent redemption feature	4,208	4,208
Convertible notes	24,721	24,721
Derivative liability	1,065	1,065
Total	¥ 25,786	¥ 25,786

Convertible Notes - Summary of Aggregate Future Principal Payments for the Convertible Notes (Details) - Dec. 31, 2018 ¥ in Thousands, $ in Thousands	CNY (¥)	USD ($)
Debt Disclosure [Abstract]
2 years to 3 years (Including 3 years)	¥ 240,212	$ 35,000
Total	¥ 240,212	$ 35,000

Commitments and Contingencies - Additional Information (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Operating lease, expenses	¥ 12,120	$ 1,763	¥ 6,081	¥ 3,113
Bandwidth
Commitments And Contingencies Disclosure [Line Items]
Future minimum payment under non-cancellable purchase commitment payment period	1 year	1 year
Future minimum payment under non-cancellable purchase commitment	¥ 1,744				$ 254
Consulting Service for Lease Term within One Year
Commitments And Contingencies Disclosure [Line Items]
Future minimum payment under non-cancellable purchase commitment payment period	1 year	1 year
Future minimum payment under non-cancellable purchase commitment	¥ 7,008				1,019
Consulting Service for Lease Term within Two Year
Commitments And Contingencies Disclosure [Line Items]
Future minimum payment under non-cancellable purchase commitment payment period	2 years	2 years
Future minimum payment under non-cancellable purchase commitment	¥ 271				$ 39

Commitments and Contingencies - Schedule of Future Minimum Payments Under Non-Cancellable Operating Leases (Details) - Dec. 31, 2018 ¥ in Thousands, $ in Thousands	CNY (¥)	USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	¥ 13,387	$ 1,947
2020	10,573	1,538
2021	4,613	671
2022 and thereafter	4,478	651
Total	¥ 33,051	$ 4,807

Share Capital - Additional Information (Details)				12 Months Ended
Share Capital - Additional Information (Details)	Jul. 26, 2018 shares	Apr. 11, 2018 USD ($) shares	Mar. 01, 2017 USD ($) shares	Dec. 31, 2018 shares	Nov. 20, 2018 USD ($)	Aug. 30, 2018 shares	Jun. 27, 2018 USD ($) shares	Dec. 31, 2017 shares
Share Capital [Line Items]
Common shares, value authorized \| $							$ 500,000
Common shares, shares authorized				50,000,000			5,000,000,000	470,393,343
Common shares, shares outstanding	42,666,670			0				42,666,670
Preferred stock, shares outstanding	27,867,937							27,867,937
Share split, ratio			0.1
Common shares, shares issued				0				42,666,670
IPO \| American Depositary Shares
Share Capital [Line Items]
Shares issued	9,060,000
Preferred Stock \| IPO
Share Capital [Line Items]
Share split, ratio	1
Common Stock
Share Capital [Line Items]
Shares issued				6,059,708
Share repurchased under repurchase plan				46,303
Common Stock \| IPO
Share Capital [Line Items]
Share split, ratio	1
Series C Contingently Redeemable Convertible Preferred Shares \| T.C.L. Industries Holdings (H.K.) Ltd
Share Capital [Line Items]
Redemption of preferred shares		1,738,720
Redemption of preferred shares, value \| $		$ 9,049,000,000
Class A Common Shares
Share Capital [Line Items]
Common shares, shares authorized				4,920,000,000				0
Common shares, shares outstanding				59,547,823				0
Common shares, shares issued				59,547,823				0
Share repurchased under repurchase plan			46,303	46,303
Class A Common Shares \| IPO
Share Capital [Line Items]
Preferred stock, shares issued upon conversion	27,867,937
Conversion of stock, shares issued	25,666,481
Class A Common Shares \| IPO \| American Depositary Shares
Share Capital [Line Items]
Shares issued	6,040,000
Class A Common Shares \| Over-Allotment Option
Share Capital [Line Items]
Common shares, shares issued						19,708
Class B Common Shares
Share Capital [Line Items]
Common shares, shares authorized				30,000,000				0
Common shares, shares outstanding				17,000,189				0
Common shares, shares issued				17,000,189				0
Class B Common Shares \| IPO
Share Capital [Line Items]
Conversion of stock, shares issued	17,000,189
American Depositary Shares
Share Capital [Line Items]
Share repurchased under repurchase plan			69,455	69,455
American Depositary Shares \| Maximum
Share Capital [Line Items]
Share repurchase plan, authorized amount \| $			$ 10,000,000		$ 10,000,000

Share Capital - Basic and Diluted Loss Per Share (Details) ¥ / shares in Units, $ / shares in Units, ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥) ¥ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 CNY (¥) ¥ / shares shares	Dec. 31, 2016 CNY (¥) ¥ / shares shares
Numerator:
Net loss attributable to Aurora Mobile Limited’s shareholders	¥ (66,197)	$ (9,627)	¥ (90,291)	¥ (61,382)
Accretion of contingently redeemable convertible preferred shares	(24,094)	(3,504)	(26,391)	(12,427)
Net loss attributable to common shareholders	(90,291)	(13,131)	¥ (116,682)	¥ (73,809)
Shares used in net loss per share computation:
Common shares - basic and diluted			42,666,670	42,666,670
Common shares - basic and diluted \| ¥ / shares			¥ (2.73)	¥ (1.73)
Class A Common Shares
Numerator:
Net loss attributable to Aurora Mobile Limited’s shareholders	(46,606)	(6,779)
Accretion of contingently redeemable convertible preferred shares	(16,963)	(2,467)
Net loss attributable to common shareholders	¥ (63,569)	$ (9,246)
Shares used in net loss per share computation:
Common shares - basic and diluted	40,441,999	40,441,999
Common shares - basic and diluted \| (per share)	¥ (1.57)	$ (0.23)
Class B Common Shares
Numerator:
Net loss attributable to Aurora Mobile Limited’s shareholders	¥ (19,591)	$ (2,848)
Accretion of contingently redeemable convertible preferred shares	(7,131)	(1,037)
Net loss attributable to common shareholders	¥ (26,722)	$ (3,885)
Shares used in net loss per share computation:
Common shares - basic and diluted	17,000,189	17,000,189
Common shares - basic and diluted \| (per share)	¥ (1.57)	$ (0.23)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Related Party Transactions - Schedule of Amount Due From Related Party (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Related Party Transaction [Line Items]
Total amounts due from related parties	¥ 4,564	$ 664	¥ 1,260	¥ 95
Focus Axis Limited
Related Party Transaction [Line Items]
Total amounts due from related parties			17	2
K K Mobile Limited
Related Party Transaction [Line Items]
Total amounts due from related parties			40	26
Stable View Limited
Related Party Transaction [Line Items]
Total amounts due from related parties			17	2
Shenzhen Weixunyitong Information Technology Co Ltd
Related Party Transaction [Line Items]
Total amounts due from related parties	1,543	224	886	¥ 65
Guangzhou Tianlang Network Technology Co Ltd
Related Party Transaction [Line Items]
Total amounts due from related parties	1,305	190	¥ 300
President
Related Party Transaction [Line Items]
Total amounts due from related parties	¥ 1,716	$ 250

Related Party Transactions - Schedule of Amount Due to Related Party (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Related Party Transaction [Line Items]
Amount due to related parties	¥ 8,864	$ 1,289	¥ 6,110	¥ 6,353
Weidong Luo
Related Party Transaction [Line Items]
Amount due to related parties			5,649	5,649
Shenzhen Weixunyitong Information Technology Co Ltd
Related Party Transaction [Line Items]
Amount due to related parties	¥ 8,864	$ 1,289	¥ 461	504
Guangzhou Tianlang Network Technology Co Ltd
Related Party Transaction [Line Items]
Amount due to related parties				¥ 200

Related Party Transactions - Schedule of Transactions With Related Parties (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items]
Services provided to related party	¥ 2,544		¥ 3,507	¥ 344	$ 366
Total	21,384	$ 3,110	2,229	2,496
Shenzhen Weixunyitong Information Technology Co Ltd
Related Party Transaction [Line Items]
Services provided to related party	1,002		2,752	344	142
Services received from related party	20,909		672	360	3,041
Office premises leased from related party	475		1,557	1,193	69
Guangzhou Tianlang Network Technology Co Ltd
Related Party Transaction [Line Items]
Services provided to related party	¥ 1,542		¥ 755		$ 224
Marketing expense incurred				¥ 943

Revenues - Schedule of Revenues (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Disaggregation Of Revenue [Line Items]
Total revenues	¥ 714,141	$ 103,868	¥ 284,709	¥ 70,322
Developer Services
Disaggregation Of Revenue [Line Items]
Total revenues	60,106	8,742	38,795	23,196
Targeted Marketing Data Solutions
Disaggregation Of Revenue [Line Items]
Total revenues	572,796	83,310	221,153	43,149
Other Vertical Data Solutions
Disaggregation Of Revenue [Line Items]
Total revenues	81,239	11,816	24,761	3,977
Data Solutions
Disaggregation Of Revenue [Line Items]
Total revenues	¥ 654,035	$ 95,126	¥ 245,914	¥ 47,126

Fair Value Measurements - Summary of Changes in Fair Value of Redemption Feature Derivative Liability (Details) ¥ in Thousands, $ in Thousands	8 Months Ended	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value of derivative liability	¥ 21,302	¥ 21,302	$ 3,098
Ending balance \| $			$ 3,224
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability		20,237
Foreign currency translation adjustment		1,065
Change in fair value of derivative liability		21,302
Recurring \| Significant unobservable inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability		20,237
Foreign currency translation adjustment		1,065
Change in fair value of derivative liability		¥ (21,302)

Restricted Net Assets - Additional Information (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)
Dividends Payable [Line Items]
Threshold limit percentage of registered capital	50.00%
PRC \| VIE
Dividends Payable [Line Items]
Restricted net asset, using statutory accounting principles	¥ 787,223	$ 114,497	¥ 280,922	$ 44,786
Minimum
Dividends Payable [Line Items]
Minimum percentage of net profit to be allocated to statutory reserve fund	10.00%

Subsequent Event - Additional Information (Details) - Subsequent Event - Shanghai Liehong Information Technology Limited Company ¥ in Thousands	Mar. 04, 2019 CNY (¥)
Subsequent Event [Line Items]
Business acquisition, agreement date	Mar. 04, 2019
Business acquisition total consideration	¥ 8,000

Condensed Financial Information of the Parent Company - Condensed Balance Sheets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Apr. 17, 2018 CNY (¥)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 CNY (¥)	Dec. 31, 2015 CNY (¥)
Current assets:
Cash and cash equivalents	¥ 576,562	$ 83,857		¥ 208,161	$ 30,276	¥ 103,168	¥ 37,570
Amounts due from related parties	4,564	664		1,260		95
Total current assets	803,730	116,897		293,358
Non-current assets:
Long-term investments	79,696	11,591		10,980
Intangible assets, net	1,531	223		283
Total non-current assets	188,338	27,393		66,092
Total assets	992,068	144,290		359,450
Current liabilities:
Amounts due to related parties	8,864	1,289		6,110		6,353
Total current liabilities	163,824	23,827		116,646
Non-current liabilities:
Deferred revenue — non-current	10,265	1,493		330
Convertible notes (including deferred revenue of the VIE without recourse to the Company of RMB nil and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	216,179	31,442	¥ 211,695	0
Total non-current liabilities	226,584	32,955		551
Total liabilities	390,408	56,782		117,197
Mezzanine equity
Total mezzanine equity				466,637		220,539
Shareholders’ (deficit) equity
Common shares				26
Treasury shares (nil and 46,303 class A common shares as of December 31, 2017 and 2018, respectively)	(3,165)	(460)
Additional paid-in capital	944,500	137,372		13,689
Accumulated deficit	(348,123)	(50,632)		(234,810)
Accumulated other comprehensive loss	8,400	1,221		(3,289)
Total shareholders’ (deficit) equity	601,660	87,508		(224,384)		¥ (108,414)	¥ (40,204)
Total liabilities, mezzanine equity and shareholders’ deficit	992,068	144,290		359,450
Parent Company
Current assets:
Cash and cash equivalents	238,236	34,650		118,429
Due from the entities within the Group	7,030	1,022		6,603
Prepayments	2,439	355
Interest receivables	89	13
Amounts due from related parties				28
Other receivables	1,717	251
Total current assets	249,511	36,291		125,060
Non-current assets:
Long-term investments	590,752	85,921		126,616
Intangible assets, net	93	14
Total non-current assets	590,845	85,935		126,616
Total assets	840,356	122,226		251,676
Current liabilities:
Accrued liabilities and other current liabilities	11,542	1,679		3,072
Amounts due to the Company and its subsidiaries	710	103		702
Amounts due to related parties				5,649
Total current liabilities	12,252	1,782		9,423
Non-current liabilities:
Deferred revenue — non-current	10,265	1,493
Convertible notes (including deferred revenue of the VIE without recourse to the Company of RMB nil and RMB nil (US$ nil) as of December 31, 2017 and 2018, respectively)	216,179	31,442
Total non-current liabilities	226,444	32,935
Total liabilities	238,696	34,717		9,423
Mezzanine equity
Total mezzanine equity				466,637
Shareholders’ (deficit) equity
Common shares				26
Treasury shares (nil and 46,303 class A common shares as of December 31, 2017 and 2018, respectively)	(3,165)	(460)
Additional paid-in capital	944,500	137,372		13,689
Accumulated deficit	(348,123)	(50,632)		(234,810)
Accumulated other comprehensive loss	8,400	1,221		(3,289)
Total shareholders’ (deficit) equity	601,660	87,508		(224,384)
Total liabilities, mezzanine equity and shareholders’ deficit	840,356	122,226		251,676
Series A Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity				26,979
Series A Contingently Redeemable Convertible Preferred Shares \| Parent Company
Mezzanine equity
Total mezzanine equity				26,979
Series B Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity				52,723
Series B Contingently Redeemable Convertible Preferred Shares \| Parent Company
Mezzanine equity
Total mezzanine equity				52,723
Series C Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity				168,317
Series C Contingently Redeemable Convertible Preferred Shares \| Parent Company
Mezzanine equity
Total mezzanine equity				168,317
Series D Contingently Redeemable Convertible Preferred Shares
Mezzanine equity
Total mezzanine equity				218,618
Series D Contingently Redeemable Convertible Preferred Shares \| Parent Company
Mezzanine equity
Total mezzanine equity				¥ 218,618
Class A Common Shares
Shareholders’ (deficit) equity
Common shares	37	5
Class A Common Shares \| Parent Company
Shareholders’ (deficit) equity
Common shares	37	5
Class B Common Shares
Shareholders’ (deficit) equity
Common shares	11	2
Class B Common Shares \| Parent Company
Shareholders’ (deficit) equity
Common shares	¥ 11	$ 2

Condensed Financial Information of the Parent Company - Condensed Balance Sheets (Parenthetical) (Details) - $ / shares	Dec. 31, 2018	Jul. 26, 2018	Jun. 27, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0			$ 0.0001
Common shares, shares authorized	50,000,000		5,000,000,000	470,393,343
Common shares, shares issued	0			42,666,670
Common shares, shares outstanding	0	42,666,670		42,666,670
Series A Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			11,111,120
Contingently redeemable convertible preferred shares, shares issued	0			11,111,120
Contingently redeemable convertible preferred shares, shares outstanding	0			11,111,120
Series B Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			7,936,510
Contingently redeemable convertible preferred shares, shares issued	0			7,936,510
Contingently redeemable convertible preferred shares, shares outstanding	0			7,936,510
Series C Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			4,999,540
Contingently redeemable convertible preferred shares, shares issued	0			4,999,540
Contingently redeemable convertible preferred shares, shares outstanding	0			4,999,540
Series D Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			5,559,487
Contingently redeemable convertible preferred shares, shares issued	0			5,559,487
Contingently redeemable convertible preferred shares, shares outstanding	0			5,559,487
Class A Common Shares
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0.0001			$ 0
Common shares, shares authorized	4,920,000,000			0
Common shares, shares issued	59,547,823			0
Common shares, shares outstanding	59,547,823			0
Class B Common Shares
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0.0001			$ 0
Common shares, shares authorized	30,000,000			0
Common shares, shares issued	17,000,189			0
Common shares, shares outstanding	17,000,189			0
Parent Company
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0			$ 0.0001
Common shares, shares authorized	50,000,000			470,393,343
Common shares, shares issued	0			42,666,670
Common shares, shares outstanding	0			42,666,670
Treasury shares, shares	46,303			0
Parent Company \| Series A Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			11,111,120
Contingently redeemable convertible preferred shares, shares issued	0			11,111,120
Contingently redeemable convertible preferred shares, shares outstanding	0			11,111,120
Parent Company \| Series B Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			7,936,510
Contingently redeemable convertible preferred shares, shares issued	0			7,936,510
Contingently redeemable convertible preferred shares, shares outstanding	0			7,936,510
Parent Company \| Series C Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			4,999,540
Contingently redeemable convertible preferred shares, shares issued	0			4,999,540
Contingently redeemable convertible preferred shares, shares outstanding	0			4,999,540
Parent Company \| Series D Contingently Redeemable Convertible Preferred Shares
Condensed Balance Sheet Statements Captions [Line Items]
Contingently redeemable convertible preferred shares, par value per share	$ 0			$ 0.0001
Contingently redeemable convertible preferred shares, shares authorized	0			5,559,487
Contingently redeemable convertible preferred shares, shares issued	0			5,559,487
Contingently redeemable convertible preferred shares, shares outstanding	0			5,559,487
Parent Company \| Class A Common Shares
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0.0001			$ 0
Common shares, shares authorized	4,920,000,000			0
Common shares, shares issued	59,547,823			0
Common shares, shares outstanding	59,547,823			0
Parent Company \| Class B Common Shares
Condensed Balance Sheet Statements Captions [Line Items]
Common shares, par value per share	$ 0.0001			$ 0
Common shares, shares authorized	30,000,000			0
Common shares, shares issued	17,000,189			0
Common shares, shares outstanding	17,000,189			0

Condensed Financial Information of the Parent Company - Condensed Statements of Comprehensive Loss (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Condensed Statement Of Income Captions [Line Items]
Revenues	¥ 714,141	$ 103,868	¥ 284,709	¥ 70,322
Gross profit	197,067	28,663	71,339	22,600
Operating expenses
Research and development	134,358	19,542	71,651	33,717
Sales and marketing	83,853	12,196	59,673	33,062
General and administrative	(71,641)	(10,419)	(32,431)	(13,480)
Total operating expenses	(289,852)	(42,157)	(163,755)	(80,259)
Loss from operations	(92,785)	(13,494)	(92,416)	(57,659)
Foreign exchange loss, net	(11,689)	(1,700)	(339)	369
Interest income	3,657	532	314	283
Interest expense	(7,054)	(1,026)	(122)
Loss before income taxes	(66,167)	(9,623)	(94,271)	(57,472)
Income tax expenses	30	4	(3,980)	3,910
Net Loss	(66,197)	(9,627)	(90,291)	(61,382)
Accretion of contingently redeemable convertible preferred shares	(24,094)	(3,504)	(26,391)	(12,427)
Net loss attributable to common shareholders	(90,291)	(13,131)	(116,682)	(73,809)
Other comprehensive income (loss)
Foreign currency translation adjustments	11,688	1,700	(7,563)	1,896
Comprehensive loss	(54,509)	(7,927)	(97,854)	(59,486)
Parent Company
Operating expenses
General and administrative	(11,941)	(1,737)	(10,076)	(2,302)
Share of losses of subsidiaries and the VIE	(72,750)	(10,581)	(79,916)	(58,167)
Total operating expenses	(84,691)	(12,318)	(89,992)	(60,469)
Loss from operations	(84,691)	(12,318)	(89,992)	(60,469)
Foreign exchange loss, net	(186)	(27)	(339)	(961)
Interest income	3,013	438	18	48
Interest expense	(6,599)	(960)
Other income	22,266	3,238	22
Loss before income taxes	(66,197)	(9,629)	(90,291)	(61,382)
Net Loss	(66,197)	(9,629)	(90,291)	(61,382)
Accretion of contingently redeemable convertible preferred shares	44,451	6,465	(26,391)	(12,427)
Net loss attributable to common shareholders	(21,746)	(3,164)	(116,682)	(73,809)
Other comprehensive income (loss)
Foreign currency translation adjustments	29,510	4,292	(7,563)	1,896
Total other comprehensive income (loss), net of tax	29,510	4,292	(7,563)	1,896
Comprehensive loss	¥ (36,687)	$ (5,337)	¥ (97,854)	¥ (59,486)

Condensed Financial Information of the Parent Company - Condensed Statements of Cash Flows (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)	Dec. 31, 2016 CNY (¥)
Condensed Cash Flow Statements Captions [Line Items]
Net cash used in operating activities	¥ (97,925)	$ (14,241)	¥ (75,532)	¥ (42,152)
Net cash used in investing activities	(139,206)	(20,246)	(28,644)	(29,928)
Net cash provided by financing activities	614,884	89,431	217,446	135,348
Effect of exchange rate changes	(9,352)	(1,362)	(8,282)	2,450
Net increase in cash and cash equivalents and restricted cash	368,401	53,582	104,988	65,718
Cash, cash equivalents and restricted cash at the beginning of year	208,276	30,292	103,288	37,570
Cash, cash equivalents and restricted cash at the end of year	576,677	83,874	208,276	103,288
Parent Company
Condensed Cash Flow Statements Captions [Line Items]
Net cash used in operating activities	16,052	2,335	(744)	(2,311)
Net cash used in investing activities	(535,995)	(77,957)	(157,412)	(77,193)
Net cash provided by financing activities	614,884	89,431	217,446	134,348
Effect of exchange rate changes	24,866	3,617	(7,695)	2,649
Net increase in cash and cash equivalents and restricted cash	119,807	17,426	51,595	57,493
Cash, cash equivalents and restricted cash at the beginning of year	118,429	17,224	66,834	9,341
Cash, cash equivalents and restricted cash at the end of year	¥ 238,236	$ 34,650	¥ 118,429	¥ 66,834

Organization and Principal Activities - Additional Information (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018 CNY (¥)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CNY (¥)
VIE
Variable Interest Entity [Line Items]
Net liabilities	¥ 20,756	$ 3,019	¥ 18,874